Jay Ajayi tore his left ACL on Sunday, according to a league source, ending the season of the Eagles' top running back – and maybe his Eagles career.

The Eagles placed Ajayi on injured reserve on Monday and claimed defensive tackle T.Y. McGill.

The devastating injury came during the final year of Ajayi's contract, diminishing his value and leaving his future with the Eagles uncertain – especially considering his history with knee injuries. Ajayi tore his right ACL during his freshman year at Boise State.

The Eagles' more immediate concern will be replacing Ajayi, who became their lead running back after top executive Howie Roseman acquired him in a midseason trade from Miami last fall. They have Corey Clement, Darren Sproles, Wendell Smallwood, and Josh Adams at running back. Clement has not played the last two weeks because of a quadriceps injury. Sproles has been out since Week 1 with a hamstring injury.

The Eagles could also be active in the trade market again, and there's no name bigger than Pittsburgh's Le'Veon Bell, who has not played this season on the franchise tag.

Ajayi, who missed the Week 3 win over Indianapolis, has 45 carries for 184 yards and three touchdowns this season. He was disappointed after carrying the ball only eight times on Sunday, but one of those carries finished with a costly fumble on the 5-yard line.

"I'm not going to ever get after Jay Ajayi," center Jason Kelce said. "That dude runs harder than anybody I've ever played with, almost. I love that guy."

It's not yet known when he injured his knee. Ajayi's last carry came at the 10-minute, 3-second  mark in the fourth quarter. He met with reporters after the game and the team did not announce he was on injured reserve until Monday evening.

Ajayi's punishing rushing style helped the Eagles during their Super Bowl run last season. He averaged 5.8 yards per carry in seven regular-season games after coming to the Eagles, and he had 184 rushing yards in three postseason games.

The Eagles had plans to feature him this season, and Ajayi viewed 2018 as a critical year in his career. Their plans changed after Monday's news, and the Eagles are left with another major obstacle this season.