Will Edinburgh be celebrating once again come the end of the weekend? © Getty Images

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News: Heineken Cup - Team of the Round

News: Heineken Cup: The race to the quarters

Matches: Cardiff Blues 36 - 30 Racing Metro | Edinburgh 34 - 11 London Irish | Benetton Treviso 20 - 26 Saracens | Biarritz 36 - 5 Ospreys | Castres 13 - 16 Scarlets | Northampton Saints 36 - 51 Munster | Clermont Auvergne 19 - 15 Ulster | Leicester Tigers 33 - 6 Aironi | Bath Rugby 23 - 18 Glasgow | Leinster 25 - 3 Montpellier | Connacht 9 - 8 Harlequins | Gloucester Rugby 34 - 24 Toulouse

Tournaments/Tours: Heineken Cup

The Heineken Cup Pool stages reach their culmination this weekend with a host of sides still vying for a place in the knockout stages of the northern hemisphere's premier club tournament.

The action starts on Friday with Aviva Premiership leaders Harlequins hoping their rivals Gloucester can do them a favour by beating Top 14 giants Toulouse. Conor O'Shea's Quins currently lie two points off Guy Noves' side and will travel to Connacht looking to keep the pressure on the four-time champions.

O'Shea has changed four from the side that overcame the Cherry and Whites 20-14 at the Twickenham Stoop last weekend. Sam Smith comes in on the wing to replace Tom Williams - who is at home with his partner as they expect the birth of their first child - while Joe Marler, Chris Brooker and Tomas Vallejos all start in the pack. Connacht, meanwhile, have opted to change just one member of the XV that faced Toulouse, with Ronan Loughrey replacing Dylan Rogers at tight-head.

Gloucester have also made just one alteration for their match with Toulouse, where Rupert Harden starts in the front-row instead of Dario Chistolini. The Top 14 champions have made five changes from the side that eased past Connacht last weekend 24-3. Yves Donguy starts on the wing in place of Vincent Clerc while Yannick Jauzion partners Clement Poitrenaud in the centres. Lionel Beauxis comes in at fly-half for Luke McAlister with the only swap in the pack seeing Yannick Nyanga in for Jean Bouilhou.

Come Saturday, the key battle of the day is at the Stade Marcel Michelin as Clermont Auvergne and Ulster go head-to-head for Pool 4 supremacy. Clermont are currently 38 games unbeaten at home and with the Top 14 giants lying three points off Brian McLaughlin's Ulster, they will be going all out for the win. Ulster, who are on 19 points, will hope to either upset the odds or secure a losing bonus point to increase their chances of finishing in the best runners-up spots for the knockout stages. Ulster took the previous clash between the two sides 16-11 but with home advantage behind Les Jaunards, they are a formidable opponent.

Ulster have made just one enforced change, with Ian Whitten named at outside-centre in place of the injured Darren Cave. Nevin Spence returns from injury on the bench. Lionel Faure, Benjamain Kayser and Clement Ric start in Clermont's front-row, while Morgan Parra and David Skrela will assume the playmaking duties at halfback.

The Pool's other match is at Welford Road with the Leicester Tigers going up against Aironi. The Tigers were on the wrong end of a 41-7 hammering at the hands of Ulster last Friday and while they are playing for pride, they will hope to end their European campaign on a high. George Chuter, Ed Slater, George Skivington and Ben Woods return in the pack for Leicester, while scrum-half Micky Young makes his first start for the club.

And elsewhere on Saturday, the Northampton Saints entertain unbeaten side Munster. Ronan O'Gara's boot was the difference between the two sides when they met in Round 1, with the fly-half nailing a last-gasp drop-goal to give his team a 23-21 win and the Saints will be hunting for revenge.

All eyes have been on Chris Ashton this week with the England winger agreeing a switch to Premiership rivals Saracens, and he has been dropped from the squad for this weekend's clash. Jamie Elliott and Vasily Artemyev start on the wings, while Ryan Lamb starts at fly-half.

Munster, meanwhile, have been dealt a blow in the past couple of days with flanker Niall Ronan ruled out for the rest of the season. As a result, Donncha O'Callaghan comes into the pack, while Donnacha Ryan shifts to blindside flanker from lock. Elsewhere, Castres host Scarlets with both sides effectively playing for pride.

Saturday's line-up is completed in Pool 3 with Heineken Cup champions Leinster looking to secure an all-important home quarter-final. Joe Schmidt's side host Montpellier - with the return clash finishing in a 16-16 draw in Round 1. Leinster sit pretty on 20 points - a full nine points ahead of second-placed Glasgow who travel to under-fire Bath in the Pool's other game.

Leinster have made a number of changes, with Eoin O'Malley partnering Gordon D'Arcy in midfield. Fergus McFadden shifts to the wing as a result, while Isaac Boss returns alongside Jonny Sexton at halfback. Up front, Jamie Hagan starts at tight-head for his Heineken Cup debut, while Rhys Ruddock joins Sean O'Brien and Jamie Heaslip in the back-row.

On Sunday, Pool 2 is poised for an epic finish. Edinburgh and the Cardiff Blues are joined at the hip on 17 points. Edinburgh have been the surprise package of this year's Heineken Cup with two epic wins over Racing Metro to their name and they entertain Toby Booth's London Irish at Murrayfield while the Blues host Metro in Cardiff.

It is possible that if both sides record wins then they can both go through with one qualifying through the best runners-up spot. And form is on the side of the RaboDirect PRO12 clubs with the Blues having overcome Racing Metro in Round 1 and Edinburgh prevailing at the Madejski Stadium.

The Blues make two changes, with Gavin Evans replacing Gavin Henson at inside-centre and Scott Andrews taking over from Tau Filise at tight-head. Edinburgh boss Michael Bradley has made just one switch for the visit of the Exiles, with Roddy Grant replacing Ross Rennie in the back-row.

Sunday's other two battles are in Pool 5 with Saracens travelling to Treviso and Biarritz hosting the Ospreys. Saracens currently sit five points ahead of both Biarritz and the Ospreys so they need a losing bonus-point to progress but will be eyeing the home quarter-final berth as a realistic goal. With Biarritz and the Ospreys neck and neck on 13 points, they will aim to secure qualification to the quarter-finals of the Amlin Challenge Cup at the very least.

James Short, Peter Stringer, Matt Stevens and Jackson Wray all return for Sarries, who are also able to call on lock Hayden Smith after six weeks out with a hand injury.