BEREA, Ohio -- Cleveland Browns quarterback Baker Mayfield has been playing with a partially torn labrum in his left shoulder, a source confirmed to ESPN on Thursday.

Mayfield suffered the injury to the non-throwing shoulder on Sept. 19 while trying to make a tackle against the Houston Texans, and has been wearing a shoulder harness since.

Mayfield is coming off arguably his worst game in almost a year. He completed only 15 of 33 passes for 155 yards in Cleveland's 14-7 victory over the Minnesota Vikings on Sunday. Still, Mayfield has downplayed both the injury and the harness, saying they "should not" be affecting his throws.

"I really do not think it's that complicated," Mayfield said of his performance against the Vikings. "Everybody is going to try and make an excuse. I pretty much hit on it after the game, I just have to make the damn play. It's that simple."

Mayfield, who finished in the top 10 in QBR last season, ranks 26th in QBR so far this season with a rating of 39.8.

The Browns, who have won three in a row, travel to play the Los Angeles Chargers this weekend.

The NFL Network first reported the severity of Mayfield's injury.