The Ospreys’ mental frailty can be used against them by Ulster this weekend, says the Irish province’s director of rugby Les Kiss.

Saturday’s showdown at the Liberty Stadium will have a crucial bearing on the final shake-up for Guinness Pro12 play-off places, with the Ospreys currently sitting in fourth spot – just a point above Ulster.

But the Liberty Stadium side have lost four games on the bounce and Kiss admits his team intend to prod at any mental scar tissue.

“The Ospreys have played some fantastic rugby throughout the year, but they’re in a space where they’re going to be asking questions and we have to make them ask deeper questions,” said Kiss.

“I would imagine they’re saying the same about us.

“A lot of the game at this time of the year is mental, a lot of it at this time of the year is emotional and when you have that battle you still have to have that steel and composure to apply your plan accurately.

“We’re going away to Ospreys who have been a top two team all year but are now stuttering.

“There is a high level of confidence and belief and that is what we are tapping into more than anything.”

But although the Ospreys may have lost their last four games in all competitions, Ulster are not on a winning streak, either.

They lost their last match 22-10 to Munster, after drawing 24-24 against Cardiff Blues and the contest could yet be tilted in the Ospreys’ favour if Wales’ new Lions tourist Dan Biggar makes an anticipated return from a facial injury after missing the Judgement Day defeat to the Blues.

Ulster will be without centre Jared Payne – also selected last week as a Lion – due to an ankle problem picked up against the Blues earlier this month.

A victory, without conceding losing bonus points, would almost certainly put the Ospreys into the semi-finals. Ulster know that defeat would likely end their ambitions of reaching the knock-out stages for the fifth season in succession.

Ospreys forwards coach Chris Gibbes said: “The Ulster match is going to be a cracker because there’s a lot on the line for both teams.

“They’ll fancy their chances and be coming here looking to have a crack at us up front.

“That’s a good challenge to meet head-on.

“They have a backline that would be the envy of most teams in Europe, with quality across the field.

“We are going to have to make sure we make our mark and make it early and make sure we take control of their threats out wide.”