Ulster Rugby has revealed that Tommy Bowe has sustained significant lateral ligament damage to his right knee in Saturday's defeat to Northampton and will undergo surgery later this week to repair the damage.
Bowe suffered the injury when landing awkwardly following an attempted tackle by Jamie Elliott late on in the tie.
Ulster's statement said: "At this stage it is not possible to put a timescale on how long his recovery period will be.
"A further update on this will be issued following the surgery, when the full extent of the injury will be known."
Ulster second row Dan Tuohy injured his calf in the same game and will be assessed tomorrow morning, as will Paddy Jackson, who sustained a dead leg midway through the second half.
An update on their fitness will be issued tomorrow afternoon but Bowe tweeted later that the injury was not as bad as he first thought.
Thanks to everyone for the messages. Will have surgery this week on my knee, it's not as bad as I feared so hopefully be back soon— Tommy Bowe (@TommyBowe14) December 16, 2012