Darren Potter will be missing for up to six weeks ahead of a huge month for MK Dons.
The midfielder, described by manager Karl Robinson as his best player so far this season, jarred his knee in training last week and will require a lengthy spell on the sidelines.
With huge trips to Middlesbrough and Burnley in the next week, Robinson will also be without Ben Reeves, Joe Walsh, Mark Randall, Dale Jennings and keeper Cody Cropper.
The American stopper picked up a knee injury while on duty with the USA U23s last week and will be out for up to eight weeks, leaving Robinson thin on the ground ahead of a tough month for his side.
“We’re going to Middlesbrough without some massive players,” he said. “Potter is out for four to six weeks. Someone had a shot in training and he went to block it and it has opened up a part of his knee. It’s a massive blow for us.
“Cody Cropper is out for six to eight weeks with a knee problem that he picked up with America,
“Ben Reeves is still out, Dale Jennings’ knee has flared up, Joe Walsh is recovering but is still not fit and Mark Randall is out for the season.”
The injury to Potter means the responsibility of the midfield orchestrator will fall on the shoulders of Diego Poyet.
The 20-year-old has impressed in his first three matches for the club since joining on loan from West Ham, and Robinson hopes he is able to step into the breach left by Potter.
Robinson said: “It’s lucky we brought him in now! But it’ll still be huge, missing Darren Potter. He’s been our best player this season.
“Diego is not Darren yet, he’s not got the experience but he’s got the quality, the understanding, and the fight and desire to be successful. I’m excited by seeing what he can do.”