Steve Tandy believes his Ospreys team face "a big test of character and attitude" when they tackle Heineken Cup rivals Northampton on Sunday.
Both sides lost their opening games - Ospreys at home to Leinster and Saints away against Castres - which has cranked up pressure for the Pool One clash at Franklin's Gardens.
"This is a big game for us," Ospreys head coach Tandy said.
"We didn't do ourselves justice last Saturday. We had the third-biggest Heineken Cup crowd of the weekend, and it is disappointing that we were not able to reward such a big turnout with a good performance.
"We are well aware that we need to make some big improvements if we are going to put in the kind of performance at Northampton that we need.
"They are in the same boat as us having also lost their first game, so no doubt there will be a tension and edge to the game. This is a very difficult group, but there is still everything to play for and there will be plenty of twists and turns.
"It's going to be a big test of character and attitude, how this group (of players) reacts to a setback.
"But we know enough about them to realise that we have big-game players in the squad, individuals who are used to pressure situations, and it will be up to them to lead by example on Sunday."
Northampton rugby director Jim Mallinder has made a number of changes from the team beaten by Castres, handing starts to wing Jamie Elliott and scrum-half Lee Dickson, together with back-row forwards Phil Dowson and Samu Manoa, while Alex Waller takes over from injured England prop Alex Corbisiero.
Exeter, fresh from an eye-catching Pool Two demolition of Cardiff Blues last weekend, travel to Glasgow on Sunday after underlining their credentials as serious quarter-final contenders.
"The way we started at the weekend against Cardiff was pretty special. That's pretty much how we want to play - a full 15-man game where we can really attack the spaces the opposition give us," Chiefs fly-half Gareth Steenson said.
"Hopefully we can do the same this week against Glasgow, but we know it will be a tough test as they are a side who are going well themselves.
"We know if we are slightly off our game, we are going to be in trouble up there."
Harlequins, having lost at home to the Scarlets seven days ago, are effectively playing for Pool Four survival against Clermont Auvergne at Stade Marcel Michelin.
And they will arrive there without flanker Maurie Fa'asavalu, who requires surgery on a hamstring injury and is not expected back in action until the end of January, while other absentees include Ugo Monye, George Lowe, Nick Kennedy and Paul Doran-Jones.
Edinburgh are also in action on Sunday, facing Perpignan at Stade Aime Giral, where victory for the Scottish side would show they mean serious business after defeating Munster last weekend.