Ulster and Ireland second row Lewis Stevenson will undergo surgery on Thursday to repair a hernia injury.
The 29-year old forward picked up the injury while on tour with the Emerging Ireland squad playing in the IRB Tbilisi Cup in Georgia.
He is expected to be out of action for 6-8 weeks following the operation.
Stevenson, who previously played for Exeter Chiefs and Harlequins, will now be in a race against time to be fit for the start of Ulster's pre-season matches.
One pre-season fixture for the 2012-2013 Heineken Cup semi-finalists includes a trip to Welford Road to take on Aviva Premiership champions Leicester Tigers.