The Ospreys' clash with Leicester Tigers in a Sunday showdown at the Liberty Stadium is one that the Welsh region simply have to win to stay in the hunt for quarter-final qualification from Pool 2 - but with Adam Jones warning they have to significantly raise their game.
The Tigers top a hugely competitive group on 14 points with Toulouse on 13 and the Ospreys on nine, Toulouse home to Benetton Treviso with this one set to go all the way to the wire in the 71st and 72nd group games a week later.
"It's obviously a big step up against Leicester," said the British & Irish Lions and Wales prop who captained the Ospreys to a last-gasp one-point PRO12 win over Zebre. "As a pack we've got to raise our game.
"We've been pretty good recently. We were good against Toulouse and we know when we're up there we can match anyone but we are going to get hammered if we turn up like we did on Friday - to be honest, we were rubbish.
"I think when we've been good recently we've been doing everything simply, but we got caught trying to play in the wrong areas. It was frustrating because we know it's going to be ten times harder on Sunday."
The two teams were level at 10-10 at half-time of their Round 2 match at Welford Road but the Tigers ran away with in the second period with tries from Manu Tuilagi (2), Toby Flood and Ben Youngs earning them a bonus point in a Pool that could well be settled on those extra points.
"We know what a good side they are," added Jones. "We were disappointed with our last 10 minutes when we lost up at Welford Road.
"You've got to raise your game. It's one hell of a side, with a hell of a forward pack."
