Castres Olympique have stormed into contention as possible Pool 4 winners - they will claim the prized top spot if they beat leaders Munster at Stade Pierre-Antoine on Saturday and do it with a superior try count on the day.

The Round 1 clash back in September ended with Munster winning 28-23 but Castres matching them 1-1 in tries. Now a try here or there could make all the difference in deciding the quarter-final line-up.

"In many ways it will be like a cup final because both sides simply have to win," said Munster captain Mick Galwey. "The big difference from a cup final, of course, being that they have home advantage...and that will be a big factor.

"When we played them in Round 1 we probably enjoyed a bit more luck than them and we only won narrowly so we have it all to do on Saturday. Knowing we are through to the quarter-finals takes a bit of the pressure off us but the statistics show that no side has won the tournament without home advantage in the quarters.

"A win in Castres will rank with anything we have achieved in the tournament so far but a neutral would have to fancy the home side in this sort of situation."

Castres, however, have an injury crisis ahead of the crunch tie. Club captain Raphael Ibañez (knee) will have to wait until tomorrow (Tuesday) for the results of further tests before finding out if he can face the 2000 Heineken Cup finalists.

And second row Frédéric Laluque (knee) and back row Guillaume Taussac (groin) are out while there are doubts over props Laurent Toussaint and Levan Tsabadze.

Jean-François Beltran, joint Castres coach who is in charge of the Round 6 Pool final against Munster said: "Winning at Bridgend was superb because it has set up this Pool final at Stade Pierre Antoine.

"Last year we had one win in the Heineken Cup, this time round we have four victories under our belt - but we have to win the fifth. It is three sets to love to Munster as it stands and we've had enough!

"Thanks to the team's performances, we have a great opportunity in front of us - to realise one of this season's objectives and qualify for the quarter-finals of the Heineken Cup.

"I think the occasion in itself will be enough to concentrate the players' minds. The ground will be full, the television cameras will be there. But it is not enough just to take part in this match. We have to win it.

"The difference between this weekend and the match last week against Bridgend is that we will have to be prepared to play on our own ball on Saturday. Against Bridgend we played a lot on Bridgend's mistakes and their lost possession but Munster very rarely lose possession, they are very strong in that area.

"Defence will be uppermost in the game. It is thanks to our good defensive work in the away match that we have the chance of contesting the outcome of this Pool in the final weekend so that is an area which can't give way on Saturday.

"In terms of players, they have a scrum half in Peter Stringer who is at the heart of the team. He hardly ever runs himself but provides a plateau for the team, until organised waves of players arrive. The boot of O'Gara is lethal.

The Munster half-back pairing is one of the best in Europe. That is one of Munster's strong points - along with their back row and their centre pairing.

"Munster will be coming to Castres looking for the number 1 spot in the Pool. We hope we can step up for the challenge and prove ourselves to be at the level of this game."