Welcome back to ESPN's live commentary of the Bahrain Grand Prix this weekend. Next up we've got qualifying and the big news since FP3 is that Lewis Hamilton has been given a five-place grid penalty.

Mercedes decided to change the rear assembly of Hamilton's car at the end after final practice following a suspected tyre delamination appeared to cause suspension damage. The gearbox is all part of the rear suspension assembly so the team is currently rebuilding the rear of the car. A change of gearbox at this stage of the weekend results in a five-place penalty.

But we haven't had an exact explanation of what happened at the end of practice. From the onboard camera it looked as though the rear stepped out as he was going down a straight. Fortunately he kept it all in check and then when the camera switched to an exterior view it was clear there was suspension damage and tyre damage. Quite whether it was the tyre or suspension that went first is not clear at the moment, but we suspect it was the tyre delaminating, which is very unusual.

So we can say that Hamilton won't be starting from pole tomorrow but the big question is who will be. Webber also has a penalty (three-places for a collision in qualifying) but Vettel is definitely in the running.

Vettel set the second fastest time in final practice but did not set a quick time on the medium tyres. On his fast lap he got stuck in traffic, but if he stood to gain as much as Alonso did from switching to the medium tyres he would have been fastest. In the end Alonso was 0.101s clear of Vettel with Webber third and Raikkonen fourth, 0.199s off the pace.

On Friday Raikkonen was fastest despite a couple of errors in the final sector so we were expecting him to be a bit quicker in FP3. He lost 0.3s to Alonso in sector two so possibly made another error and it will be interesting to see if he can take pole with a clean lap in Q3.

A little further down the grid, the Force Indias are looking like very strong contenders for a top-ten grid position, especially once the penalties of Hamilton and Webber are applied.

McLaren meanwhile are struggling for pace this weekend. The layout appears to be exposing the deficiencies of the car, although Button was within a second of Alonso in final practice. A top-ten grid position will be seen as a success and then the team will be hoping a good strategy will yield for some solid points to take into the three-week break ahead of the Spanish Grand Prix.

Here's a closer look at the delaminated rear tyre on Hamilton's car and the broken suspension after FP3.

© Sutton Images

Engines are now being fired up in the garages with just ten minutes ahead of Q1.

It will be interesting to see what tyre strategies teams adopt in Q3. In China we saw Vettel, Button and Hulkenberg opt to either set times on the harder tyre or not set a time at all in order to start the race on the harder rubber. Here the softer compound (the medium) is lasting much longer than the soft did in China, so it's likely we'll see a more straightforward approach in Q3 with drivers attempting to set the fastest lap possible.

Pirelli is expecting two-stop or three-stop strategies this weekend but a two-stop is probably more attainable for most teams than it was in China, so it will be a tough choice.

Reports from the circuit say Pirelli has said the tyre failed first on Hamilton's car. That will be a concern for the Italian tyre maker, which has had a very good record in the sport in terms of failures since joining in 2011. They are still investigating the exact cause for the delamination.

Hamilton is getting ready in the Mercedes garage so at least the car looks ready for the start of this session after its rebuild.

The pit lane is open for the start of the session. No cars heading out just yet...

In China we had a very lengthily wait for the first action in Q1, hopefully the wait won't be quite so long here.

Gutierrez has his eyes closed in his cockpit as he mentally prepares himself for the start of the session. Lots of pressure on him this weekend after his clumsy crash in China.

And Gutierrez is the first to head out. He also hasn't set the world alight with his pace so plenty to prove in the next hour. He's on the hard tyres, as is team-mate Hulkenberg who has joined him.

Rosberg, the Toro Rossos and van der Garde are also out on track now.

Hulkenberg sets a 1:34.409 but that was on the hards. We can expect him to go a bit quicker on the mediums later in this session.

Raikkonen, Grosjean and Massa have joined the fun now.

Van der Garde says something is in his cockpit by his legs. Not ideal when you are trying to set a quick lap.

Rosberg sets a 1:33.364 to go fastest, Grosjean second with a 1:33.498. Both set their times on hard tyres.

Raikkonen runs wide in turn one as he attempts a fast lap on the hards. He will have to go again.

The top teams will be looking to make it through this session without using a set of medium tyres.

Massa is third fastest on 1:33.780.

Perez heads straight out on the medium tyres, which is indicative of how much McLaren is struggling this weekend.

Button is also on the medium compounds as Alonso starts his lap on hards.

Di Resta complains of a lack of communication from the pit wall, most likely because he's struggling with traffic.

Hamilton has gone out on hard tyres but Webber has gone straight out on mediums. We're still waiting for Vettel to appear.

Vettel is now on track and also on the mediums. It will be interesting to see how they approach race strategy with the tyres this weekend.

Button goes eighth fastest with a 1:34.071 on medium tyres, Alonso is fastest with a 1:32.878 on hards.

Webber goes just seventh on the mediums with a 1:33.966. Not good for him.

Button is complaining of a lack of front grip. Q3 could be difficult for him to make.

Hamilton has backed off or had a mistake in the middle sector on his first attempt so will have to go again.

Vettel is second fastest on the mediums with a 1:33.327 so is 0.5s off Alonso despite being on the mediums.

Replays show that Vettel's lap was pretty scrappy and that Hulkenberg has just made a mistake after switching to mediums.

Hamilton pops up fifth after getting a clean lap on the hard tyres.

At the moment Gutierrez and Ricciardo are in the drop zone. Both are still on track and Ricciardo is on a faster lap.

Maldonado and Bottas have identical times but Maldonado is behind as he set his lap after Bottas.

Ricciardo puts himself up to 12th and is safe. Looks like Malonado and Gutierrez are dropping out with the bottom four.

Yep, Maldonado, Gutierrez, Pic, Bianchi, van der Garde and Chilton drop out in Q1. Caterham beats Marussia in the battle at the back but more disappointment for Sauber and Gutierrez, who was only 0.5s ahead of Pic's Caterham.

Van der Garde was 0.9s off team-mate Pic who was nearly a second clear of Bianchi.

A replay shows Maldonado ran wide at turn 10 on his final attempt. He drops out despite setting an identical time to Bottas with a 1:34.425.

Ben asks: "Who is facing grid penalties this week?"

Hamilton - five places for a gearbox change
Webber - three places for a collision with Vergne in China
Guttierrez - five places for a collision with Sutil in China

Gutierrez's will be applied first, then Webber and finally Hamilton's as that was the order that the penalties were dished out. That means Gutierrez will start at the back of the grid tomorrow.

It looks like there has been a flash fire in the Marussia garage as Bianchi's car is doused in extinguisher water. No obvious damage to the car of garage, but a bit of a concern for the team.

Webber heads out on medium tyres that look like the ones he used in the last session. Vettel is also out on used mediums.

The Force Indias, Toro Rossos and Hulkenberg are also on track at this early stage in Q2.

Anton asks: "I find it interesting that the weekend Kovalainen comes back to Caterham, and they're suddenly back in the fight with Marussia instead of just getting trounced. An interesting coincidence and due simply to updates, or are his experience and inputs actually bringing them back up again?"

They have a lot of updates this weekend and Kovalainen came in to help give feedback on them in FP1. So a little of both, but probably more to do with the successful updates.

Webber sets a 1:33.907 on his used tyres. That time will be beaten when they bolt on fresh mediums.

Vettel beats it immediately on his used mediums with a 1:33.471. However, that's still slower than Alonso.

Di Resta sets the fastest lap with a 1:33.335 on medium tyres.

It looks like most drivers have now opted for the mediums, Raikkonen goes fourth fastest on his but made a mistake in sector two.

Alonso goes fastest with a 1:33.316 on the mediums, but he is still not as quick as he was on the hards.

Rosberg is on a quick lap, as is Hamilton. Both are on mediums. Rosberg was fastest through sector one and is fastest again in sector two....

Hamilton goes third fastest. Webber has just gone out on new mediums.

Rosberg sets a 1:32.867 on the mediums, which is the fastest of qualifying so far. Impressive lap.

Perez, Hulkenberg, Ricciardo, Bottas and Vergne are all in the drop zone. Grosjean is about to set his first time of Q2

Grosjean goes seventh, demoting Button to the drop zone.

Button is currently 0.2s off Sutil in 10th but both are on track for another go. Only Rosberg, Alonso, di Resta and Hamilton are confident enough to stay in the garage.

Webber goes second fastest with a 1:33.098 on his new mediums.

Raikkonen isn't far off the drop zone - only 0.23 ahead of Button. He is behind him on track as both attempt another run.

Ricciardo goes ninth with a good lap but there are some fast cars behind him on a lap.

Sutil goes sixth as Vettel goes fastest with a 1:32.746.

Button in the top ten, Raikkonen improves and Grosjean has been knocked out.

Button makes it through to Q3 with a good lap. Grosjean just missed out by 0.060s ahead of Perez in 12th, Ricciardo in 13th, Hulkenberg in 14th, Bottas in 15th and Vergne in 16th.

A second splits Vettel and Button in the top ten, so it should be a tight Q3 session. Button celebrates on the radio showing just how tricky McLaren have been finding it this weekend.

Impressive times from Vettel and Rosberg. Those two and Alonso are the only three to make it into the 1:32s but Alonso was on hards rather than mediums and did it in Q1. Q3 should be very interesting.

The session gets underway with di Resta and the two Mercedes going out on mediums.

Alonso also joins the fun on the medium tyres, but we don't know whether those are the same ones he used in Q2. All the drivers will most likely save a set for a fast lap right at the end of the session. We know Red Bull have used two sets of mediums on each car, so those two probably won't emerge until the very end.

Di Resta is the first to set a lap but Rosberg is much faster with a 1:32.543 - the best we've seen today.

Alonso sets a 1:32.667 but we reckon those are used mediums compared to Rosberg's fresh ones.

Hamilton third fastest with a 1:32.762, which is a personal best for him this weekend.

Sutil went out but did not complete a lap.

Vettel, Webber, Massa, Button and Raikkonen did not head out for that first run. Give it a couple of minutes and we might even see ten cars on track at once.

Webber is the first to leave the pits for his final run. Sutil follows him out.

Raikkonen and Rosberg also out on new sets of medium tyres.

Massa heads out on the hard tyre, Alonso is on the mediums. Massa will start the race on the hards then, but it will be interesting to see how high he can qualify it.

Webber starts his lap first. He has a clear track and DRS activated as he crosses the line.

Webber makes a mistake in turn eight. It's looking a bit scrappy out there for him and that's before he adds his three-place penalty.

Webber only manages fourth fastest.

Rosberg is on a very quick lap.

Raikkonen seventh.

Rosberg is faster than Vettel and has provisional pole.

Alonso makes a mistake on his final lap and bails out. Mercedes and Rosberg on pole.

Rosberg was 0.2s faster than Vettel with a very impressive lap. Alonso's earlier attempt was 0.3s off the Mercedes.

Hamilton was fourth fastest but will start ninth when he penalty is applied. Webber will start seventh, with Raikkonen to eighth, Sutil sixth, di Resta fifth and Massa - on hard tyres - fourth. Great lap by Massa for Ferrari.

It's all shaped up nicely for the race tomorrow. We'll be back then with more live commentary but in the meantime will bring you all the reaction to qualifying from the drivers and teams. Stay logged on.