Former England centre Brad Barritt has warned the Ospreys that Saracens intend to elbow them aside this weekend as they defend their European crown.

Anything less than victory for Sarries will end their hopes of emulating Toulon by winning a third successive trophy, while the Ospreys also need a win to keep alive their hopes of progress.

Both clubs have won twice and lost twice in Pool Two, but the Ospreys are in second spot behind leaders Clermont Auvergne thanks to the bonus points earned in back-to-back victories over Northampton.

That gives the English giants no margin for error at the Liberty Stadium on Saturday, but there are signs they are coming back to form with three straight victories in the Aviva Premiership which followed a stunning sequence of seven straight defeats in all competitions.

They also have a number of their big guns back from injury, including Liam Williams who will make his return from injury on the left wing for his first appearance since November 18.

Barritt said: “I think everyone understands the situation, it’s almost a fourth round knockout game; it’s essentially a knockout game before the customary knockout stages.

“But we come into the game off the back of a good performance and a good victory last weekend, we have as close to our strongest outfit out, having had quite a few injuries throughout December.”

“We know what sort of threat Ospreys pose, they are a fantastic team, well coached and with a sprinkling of internationals in the team so to go down to Swansea is going to take a huge effort from us.”

Last weekend yielded an impressive Saracens performance against Wasps in Coventry and Barritt says he feels there is more to come from arguably the strongest playing squad in the tournament.

“The game against Wasps was our best performance from the last couple of months. I think last week was a pretty married up performance in terms of what we expect from our defence, what we expect from our attack and how we like to apply pressure on teams.

“There’s still lots to come from this team and a there’s still a few guys making early returns from injury who can take us to another level this weekend.”

One of those big names who returned to fitness was England No. Billy Vunipola, who the Ospreys must face without injured Wales back rower and defensive specialist Dan Lydiate.

Saracens coach Mark McCall described Vunipola’s performance on his comeback from knee surgery in last Sunday’s 38-15 win at Wasps as “extraordinary”.

Vunipola said: “It was good to be back, I just enjoyed being out playing again and to get the win like we did was awesome as well. It’s good to get a great win and hopefully we can carry it into the game against Ospreys.”

After losing their opening two matches the Ospreys were written off by some, but two bonus point wins against Saints and Clermont completing the double over Sarries has brought them back into the qualifying mix.

Ospreys coach Steve Tandy said: “Bringing Saracens here in Europe, knowing the fact we’ve still got a chance to get to a quarter-final, says everything about this playing group.

“When everybody writes you off in Europe you go out with a little bit more freedom. Now there’s a little bit more pressure on us.

“If we beat Saracens we could knock them out and it’s just how we keep our calm and control under that kind of pressure.”