Second row Franco van der Merwe Ulster's chief injury concern ahead of Friday's PRO12 semi-final at Glasgow Warriors.
The South African underwent a scan yesterday to ascertain the extent of the damage he sustained in last Saturday's 32-10 defeat to the same opposition Ulster must beat to book their place in the Kingspan Stadium final on May 30.
The 32-year-old limped off early in last weekend's game with what is thought to be muscular damage to his lower leg and was later seen on crutches.
Should Van der Merwe miss out then Neil Doak would be going into Friday's make-or-break encounter without one of his chief lineout operators and he is already missing another key player as the second row's fellow countryman, tight-head prop Wiehahn Herbst, is out for the what remains of Ulster's season due to a foot injury picked up against Munster.
Doak is expected to have Jared Payne, Darren Cave, Callum Black, Dan Tuohy and Craig Gilroy all back in action for Friday night.
Gilroy, who lifted the Try of the Season accolade at Sunday night's PRO12 awards dinner in Dublin, has spoken of his delight to have won a public vote for his stunning score against the Scarlets, but his sole focus is now on Friday night and bagging that place in the final for a shot at silverware.
"Awards like that are nice, but ideally at the end of the season it would be nice to pick up something a little bit bigger collectively," he said.
On a lighter note, Gilroy - who is the PRO12's joint top try scorer with Rhys Webb of the Ospreys on 11 touchdowns - also revealed that he has been in touch with the Warriors' former Ulster winger Tommy Seymour ahead of the crunch clash.
"I was trying my best to get some info out of Tommy and I've been texting him, but he wasn't giving me anything," said Gilroy of the player who could well be his opposite number on Friday night.
"It's almost like the semi-final is a final itself," Gilroy also admitted.
"You don't want to look too far ahead, but it is a massive advantage for anyone to then have a home fixture for the final.
"Making the final would be great, but we've got to get there. That's all we are focusing on at the minute and it's a massive hurdle."