NEW ORLEANS – New Orleans Saints quarterback Derek Carr suffered an oblique injury in Monday night's loss to the Kansas City Chiefs, a source confirmed to ESPN.

An MRI performed on Tuesday confirmed that the injury was to Carr's oblique arm, according to the source. The quarterback had said he believed he suffered the injury while throwing an incomplete pass late in the 26-13 loss, but would need further testing to confirm.

The source declined to provide a timeline for how long Carr will be sidelined.

Oblique injuries typically lead to absences lasting several weeks. The Saints will play two games over the 10 days – Sunday against the Tampa Bay Buccaneers and then Oct. 17 against the Denver Broncos on “Thursday Night Football.”

If Carr is unable to play, either rookie Spencer Rattler or Jake Haener would take his place. Haener replaced Carr against the Chiefs.

The oblique muscles, or abdominal muscles, can affect a quarterback because most of his throwing power comes from his core muscle and not his arm. Carr said he left the Chiefs game not because of pain, but because he wouldn't be effective when he returned.

“It wasn’t like dealing with pain. … I just can’t do what I want to do,” he said at the time.

Former Saints quarterback Drew Brees returned from a left hamstring strain after a two-week absence from practice before the 2014 season. Brees, who was 35 at the time of the injury, later admitted that his mechanics had suffered and that he had developed bad habits that season after rushing to get back into the team before he was fully healthy .

Carr suffered four major injuries in New Orleans despite not missing any time last year. He sprained the AC joint in his shoulder against the Green Bay Packers in Week 3 of last season and was concussed twice last year in losses to the Minnesota Vikings and Detroit Lions.

Carr was diagnosed with a left groin injury in Week 4 this season.

NFL Network first reported the news that these additional tests confirmed Carr's injury was to his oblique area.