Ulster have released an injury update ahead of this week's game against Cardiff Blues that reveals centre Luke Marshall will miss six weeks of action.
The Ireland international back had surgery on Friday to repair ligament damage in his thumb (right hand). Ulster say the surgery was successful.
Meanwhile the province gave further updates on second-row Dan Tuohy, back-row Robbie Diack, fly-half Sam Windsor and centre Stuart Olding.
"Dan suffered concussion during the Edinburgh game on Friday night and will follow the return to play protocols," read the Ulster statement.
"Robbie suffered a muscle tear in his thigh. He is continuing to rehab but is unlikely to be available for selection this week.
"Sam has returned to full training and is available for selection this week.
"Stuart is progressing well with his rehab. He is scheduled for a review with his surgeon next week, when a better prognosis will be available."