The Ospreys are sweating on the fitness of star duo Ashley Beck and Justin Tipuric ahead of the crunch Heineken Cup clash with Leicester Tigers.
The Swansea-based region must maul the Tigers to keep their European hopes alive but could be without the international pair.
Beck is unlikely to recover from an ankle injury in time and Tipuric's chances are rated at 50/50.
"Tips is doing some rehab and is 50-50, but we are waiting on some extra information on Ashley Beck, who is a real doubt," said Ospreys head coach Steve Tandy.
"Tips has been huge for us, Becky, too. It something we've had to get used to this season, with senior players missing, people like Ian Evans, Alun Wyn Jones, Aaron Jarvis and Hanno Dirksen.
"If we lose Beck and Tips it will be a huge task for us, especially given the limited squad we have. But it's something we have to prepare for and we are going to give it a right old go."
Tandy was more hopeful of having Tipuric available for selection but he insists he will take no risks despite the magnitude of the game.
"There's always that temptation but we won't put the group before the player," said Tandy.
"If he's not right, he's not right. There are educated risks in what we are doing, but I need to sit down with the physio and see where they are come Friday.
Tom Issacs is set to fill the void left by Beck and Sam Lewis is a front-runner to start if Tipuric fails to recover.
And Tandy insists the Ospreys are confident of the duo coming in and producing the goods.
"We have no issues with TI (Isaacs) starting at 13 this weekend. He did really well for us there against the Scarlets earlier in the season.
"We'll weigh things up in the back-row, but we have a boy in Sam who's outstanding every time he wears the shirt.
"He was out on his feet at the end of the Zebre game, especially after his performance against the Dragons. He is developing all the time.
"You find out more about people on these big occasions and we are keen to develop from within. I know if Sam has to step into the role he won't let us down."
As the countdown continues for RWC2015, Tournament Chief Executive Debbie Jevans visited the Millennium Stadium to discuss preparations for the eight matches and reveal the positive news that 100,000 tickets for games at the home of Welsh rugby have sold in the last seven days.
Jason Harries is targeting a first win on the World Series circuit this season with Wales. The series returns to action this weekend in Dubai where Harries is part of a team hoping to build from its efforts in round one in October.
Wales skipper Jevon Groves says his side have addressed a few points from Gold Coast and aim to 'hit the ground running' in the next two rounds of the World Series, kicking off with this weekend in Dubai before heading off to South Africa next week.
Wales Sevens manager Steff Thomas is hopeful his side can build from a quarter-final spot in the opening round of the World Series in Australia when his side take part in the forthcoming double header in Dubai and South Africa.