Ireland boss Joe Schmidt is desperately holding out hope that Tommy O'Donnell's hip injury will not end his World Cup dreams.

Munster flanker O'Donnell was carried from the Millennium Stadium field on a stretcher in the closing stages of Ireland's 35-21 victory over Wales in Saturday's first World Cup warm-up match.

Schmidt admitted Ireland have a nervous wait on O’Donnell’s prognosis, with the 28-year-old a serious doubt for next month’s World Cup.

Ireland start their Pool D battle against Canada in Cardiff on Saturday, September 19, and O’Donnell is at best likely to face a race against time to be available.

“Tommy’s gone to the hospital to get a scan,” said Schmidt. “At the moment we know he’s hurt his hip but we don’t know what the injury is and we’ll know more about that in the next 24 to 48 hours.

“The frustrating thing for Tommy is that he made 14 or 15 tackles, he got at least three, maybe four or five turnovers.

“I thought he started the game really strongly and he’s such a dynamic player for us that we’re just going to cross our fingers and wait and see to be honest.”

Should O’Donnell’s injury prove as serious as first glance, then Ireland’s back-row picture will clear up considerably.

Ulster flanker Chris Henry would then likely take the fifth back-row slot in Ireland's final 31-man squad, alongside Jamie Heaslip, Peter O'Mahony, Sean O'Brien and Jordi Murphy.

Schmidt confirmed Andrew Trimble suffered a "mild foot sprain" and will not be sidelined for long, before praising the exploits of Munster duo Keith Earls and Donnacha Ryan, both back in Test action for the first time in 29 months.

Earls and Ryan are now serious contenders for Ireland’s final World Cup squad, with Schmidt ready to trim his training squad by as many as seven players next week.

Former Leinster boss Schmidt insisted that anyone culled from the squad next week will not have their World Cup hopes entirely dashed, with provincial matches in two weeks' time acting as extra de facto auditions.

“Keith Earls got player of the match but Tommy (O’Donnell) did well and Donnacha Ryan got through a massive amount of work,” said Schmidt.

“Donnacha bosses the lineout really well for us, we’re delighted he finally got onto the pitch for us.

“I think by the time we announce the team for Scotland, and we’ve made some decisions about who’s going to play against Scotland on Thursday we may have an idea of another four or five potentially who will work away.

“If we release some players back to their provinces, Ulster play Leinster and Munster play Connacht and we’ll be at those games, and if they don’t fit into getting an opportunity with us we’ll still get to see them in those games and that way we can cover a little bit more game time and players can get that opportunity to impress in either environment.

“They’ll obviously want to impress in our environment because the level will be a little bit more demanding.”

Schmidt admitted to being daunted by the prospect of preparing to sit down and inform several players they are surplus to World Cup requirements.

“Inevitably there has to be some communication as to how and why a decision might be made,” said Schmidt.

“Sometimes those decisions are very difficult to make and very tight, so they are not great conversations to be honest and they wouldn’t be my favourite part of the job by a long shot.

“But they’re part of the job and it’s part of the respect I have for the players that they’ve committed to our programme so far, are working really hard, and the least you can do is make sure that communication is as clear as it can be, as candid as it can be, but probably conciliatory as well, because I know how hard they’re working.”