Ulster and Ireland three-quarter Jonathan Bell is facing a late fitness battle for Friday's crucial Celtic League match against Llanelli at Ravenhill.
Bell injured his knee in last week's 25-6 home win over Cardiff in the Heineken Cup and Ulster coach Alan Solomons, who already has wing Tyrone Howe out for three months with a torn hamstring, said: "We will have to wait until later in the week to see if he will be fit."
Ulster and Llanelli, along with Neath, are competing for the last two quarter-final spots from Pool A.
Solomons said: "We have to win -it's as simple as that. Llanelli are a top quality team and we are going to have to play at our best to beat them."
Llanelli director of rugby Gareth Jenkins has warned his side they must cut out the errors which cost them dearly in the 54-38 Heineken Cup defeat by Bourgoin in France.
"Three of those errors cost us points and we must cut them out. It's no good having most of the play if you don't convert it into points.
"The players were disappointed and this match gives them a perfect opportunity to redeem themselves," he said.