Harlequins stunned four-time champions Toulouse 31-24 on Sunday to reignite their European Cup quarter-final hopes just a week after the French giants had seemingly delivered a fatal blow on the English side. Harlequins out-scored their hosts three tries to two and bravely hung on in the closing stages when they were reduced to 14 men following a yellow card for No 8 Nick Easter. Ahead 15-10 at the break, courtesy of Mike Brown and Joe Gray grabbing tries to Yoann Maestri\'s lone reply, Toulouse briefly took a 19-15 lead in the second period. But full-back Brown added his second try against the run of play for a 20-19 advantage which soon became 25-19 thanks to the nerveless conversion and penalty kicking of former All Black Nick Evans who ended with 16 points. Toulouse scrum-half Jean Marc Doussain cut the deficit to just one point with a try 11 minutes from time, but dogged defence and two late Evans penalties gave Harlequins a famous victory. The French side still lead Pool Six with 13 points while Quins are a point further back with two games to play. \"We knew we had to win here to stay in the European Cup. It was do-or-die,\" said Harlequins skipper Chris Robshaw whose side lost 21-10 at home to Toulouse last weekend, a defeat which ended their 14-match unbeaten run. \"Last week we were in too much awe of them but today we gave it everything. We stuck in there especially in the second half when they seemed to be gaining the momentum.\" Toulouse\'s defeat came on the day when they became the first club to break the one million fans barrier for home games in the European Cup. \"Toulouse have been setting the benchmark for clubs around Europe ever since they entered the European Cup back in 1995. Where they have led, others have sought to follow,\" said European Rugby Cup chief executive, Derek McGrath. \"Becoming the first team to attract one million fans is another significant milestone for Toulouse.\" Meanwhile, two-time champions Munster maintained their perfect record with a fourth successive win by seeing off the Scarlets 19-13. In a tight first half, two penalties from Ronan O\'Gara against one for opposite fly-half Stephen Jones, gave Munster a 6-3 lead at the interval. O\'Gara, playing in his 101st European Cup tie, landed another penalty after the break before James Coughlan charged over from a driving maul while Scarlets were down to 10 men when Jonathan Edwards was in the sin bin. Ken Owens\' try gave the Scarlets hope after Rhys Priestland and O\'Gara had exchanged penalties but the Irish province clung on and they now have a five-point lead at the top of Pool One. Northampton, last season\'s runners-up, crushed Castres 45-0 to record their first win after three defeats in Pool One. Greig Tonks, Ben Foden (2), Mike Haywood and Vasily Artemyev all scored tries for the Saints.