Biarritz Olympique found their away form just when it mattered most - but star full back Nicholas Brusque believes they will have to be even better at home.
Biarritz's stunning 21-17 victory over double champions Leicester Tigers at Welford Road was only the French club's fourth away win of the season.
Now they take on defending champions London Wasps at Parc des Sports Aguilera on Saturday knowing a home win will take them into April's prestigious quarter-finals.
"We are a bit scared it could wrong next weekend," said Brusque. "But we are confident playing at home and we know our fate is now in our own hands.
"Leicester is a very, very difficult place to go to and win, but we know we are going to have to play even better this weekend when we play London Wasps. We know it will be difficult against them.
"But there is a big prize for us if we win. We've reached the quarter-finals in the last two seasons, but now we have the chance to earn a home tie for our supporters. That's very important to us.
"The Heineken Cup is a big competition and we want to go a step further than we have in the past.
"A few of our players are coming to the end of their careers so it would be great for them to go out on a high by reaching the Heineken Cup final.
"We know we will have to concentrate for the full 80 minutes against Wasps. We dropped off in the final 20 minutes against Leicester at home in Round 2 and allowed them back into the game."
Biarritz's Welford Road stunner leaves them on 18 points, London Wasps on 15 and Leicester Tigers - who travel to Italy to meet Rugby Calvisano - on 14.
But Biarritz coach Patrice Lagisquet considers the job only half done.
"While it was a very big performance for us at Leicester, we know we now have to go on and beat London Wasps to complete the job," he said.
"We knew we had to win at Welford Road to be in with a chance of playing Wasps for first place in the Pool.
"But beating Wasps will be even harder than beating Leicester. Their defence is so strong and we have trouble adapting to that because teams in France don't defend like that.
"Those opening 30 minutes against Leicester were the best we've had in the Heineken Cup.
"Leicester came back at us in the second half and the only thing that gave me confidence was that we were tackling desperately and they were knocking-on.
"One of the problems with this team is that it sometimes doesn't remain lucid for the full 80 minutes. We found that against Wasps in the first round and it has happened in a number of French
"We know how difficult it is going to be against Wasps and we know we will have to concentrate throughout the game against them."
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