JJ Hanrahan and Chris Cloete are doubts for Munster's European opener against Ospreys this weekend, according to head coach Johann van Graan.

The pair both started in Saturday's Guinness Pro14 victory against Ulster at Thomand Park, but failed to make the end of the game after picking up knocks.

Hanrahan injured his hamstring in the first-half, with van Graan admitting that he only has an "outside chance" for the game at the Liberty Stadium.

"JJ went for a scan last night," he told RTÉ Sport's Michael Corcoran.

"They didn't come back too badly. There is obviously some damage to the hamstring, but it doesn't look long-term.

"He has an outside chance for this weekend, hopefully next, but it's a hamstring, so we'll just give him every opportunity for this week."

Flanker Cloete came off in the second-half, and he was still suffering from the effects of a knock which has kept him out of training, so far, this week.

"Chris still had some symptoms yesterday, so we'll look after him pretty well," confirmed van Graan.

"We are very safe when it comes to head injuries. As soon as he's ready to return to training we'll get him back in.

"At this stage he hasn't been back to the field yet.

"There are one or two (other) knocks, it was a pretty tough game on Saturday evening (but) there's nothing other serious to report, in terms of the weekend.

"So we'll just take our time, and make our calls on Thursday."