U’s head coach Karl Robinson told the Oxford Mail: “You’re talking about three months (out).
“Sometimes you can come back quicker, but the likelihood is it can be a bit longer. It’s purely on the healing process.
“Grade three is probably as bad as it gets in a hamstring injury without it completely tearing. We’re disappointed for him, obviously.
“I think since he’s come back in the summer he’s really shown a tremendous tenacity and he’s grown as a person and a player. For him to do that in that moment is a bit of a freak, but it’s one of those things, unfortunately.”
The midfielder, who arrived from Derby last summer, hasn’t been a regular since his move to Oxford, and his appearances this season have often come from the bench.
And despite a hefty fee paid by the U’s for his services, his performances have often come under scrutiny. But, the midfielder, who can also cover at right-back, will be missed as Robinson’s side look to find a winning return in the league.