Harry Pell will miss the next few weeks due to his Achilles injury
The U's influential midfielder started the opening game of the season, but has been missing from the line up since due to the issue with his Achilles.
He wasn't expected to be out for too long, but that prognosis has changed this week.
Physio Shayne O'Reilly explained: "It's a big blow for us, and Harry as an individual."
"When he came off in the Port Vale game, it looked like a case of tendonitis in the Achilles and the original scan backed that up.
"It didn't seem to be easing up though, so we sent Harry to see an Achilles specialist in London to have another look.
"He discovered a little issue, and now Harry has had a Sugar Injection and has been put in a boot.
"He will be in a boot until the middle of September, and will then be working hard to get back in action as quickly as possible - without rushing back before he's ready of course."