Former Ireland international Paddy Wallace insists that Ulster’s clash with Ospreys this afternoon is the province's biggest game of the season.

Ulster face the Welsh side at Kingspan Stadium with a place in next season’s Champions Cup at stake and for Wallace, it’s a must win game with the prospect of defeat a terrifying one.

"It’s huge for both teams," Wallace said on RTÉ 2fm’s Game On.

"Ulster’s season seemed to be over at one stage but they came into a decent run of form coming into the end of the season and were pushing for that play-off place but they’ve fallen into this qualifier and it’s huge for both teams.

"From a monetary point of view and for the fans and the players you’re trying to recruit, it’s very important to get into this Champions Cup and Ulster have never been in the Challenge Cup before.

"Ulster are going to need everything they have in the locker to go and beat the Ospreys because there’s just as much riding for them on the match as there is for Ulster.

"Dan Biggar’s in great form, they’re bringing Dan Lydiate back in after a long injury lay-off so they have that experience."

Robbie Diack, Callum Black and Charles Piutau will play their final games in Ulster colours, but the province have big absentees elsewhere on the pitch.

Rory Best and Iain Henderson have both been ruled out through injury, leaving a gap in terms of experience and cool heads, and Wallace is concerned that their absence will be keenly felt, particularly when it comes to on-pitch leadership.

"It’s difficult to pin-point where [the leadership] will come from," he said.

"Alan O’Connor has worn the captain’s armband a few times this season, Rob Herring’s coming back in, he’s going to captain the side and they’ll be boosted by John Cooney coming back in.

"They’ll be boosted by the fact that Charles Piutau will be available, he has that ability to strike from anywhere which will be important as well."