The home side, who were battling to keep alive their hopes of reaching the last eight for the first time in their history, led 6-3 in the first half before Fergus McFadden levelled the scores with the last kick of the opening 40 minutes.

McFadden took over the kicking duties when Jonny Sexton, who landed one monster penalty from a metre inside his own half, picked up a strain and the centre ended with 10 vital points.

Leinster, who had won three and drawn one of their four pool matches in 2011, found the Warriors defensive line in combative mood and could find no way through until a cruel bounce of the ball paved the way for Rob Kearney to notch the opening try three minutes after the beak.

A neat cross kick from left to right into the home 22 gave Kearney something to chase and the ball bounced up to give him the chance to snatch the ball out of the arms of Stuart Hogg. McFadden added the extra and Leinster were in front for the first time.

But Aly Kellock’s men were in no mood to surrender and came storming back into the game after Duncan Weir and McFadden had exchanged penalties. They spurned another penalty shot and instead kicked for a close range line-out.

The forwards drove ever closer to the line and then replacement scrum half Colin Gregor crossed in the left corner. Up stepped Weir to take the touchline conversion and over went the kick to level the scores with 17 minutes to play.

Now it was anyone’s game and the champions had to dig deep to book their safe-passage into the last eight. They worked their way up to the home line and their own replacement scrum half, Isaac Boss, twisted through a tackle to reach the line at the posts and claim and try that was eventually confirmed by the TMO.

McFadden added the simple conversion and now it was the Warriors’ who had their backs to the wall. They piled on the pressure, reached the Leinster 22, but couldn’t find the score they needed level the scores again.