New York Jets guard Kelechi Osemele, one of the team's key off-season acquisitions, is having season-ending shoulder surgery, a source confirmed Tuesday.

Osemele, 30, whom they acquired in a March trade with the Oakland Raiders, was injured in a full-pads practice during the run-up to their Week 5 game against the Philadelphia Eagles. Coach Adam Gase noted at the time the injury was potentially serious.

Alex Lewis has started the last two games at left guard, and has received high marks from the coaches. He likely would've replacing the struggling Osemele at some point anyway.

The Jets traded a fifth-round pick for Osemele and a sixth-round choice, thinking the two-time Pro Bowl selection would upgrade their line. Now it appears he will be one-and-done. He's signed for 2020, but it's highly unlikely he will return. He's due to make $11.4 million in base salary, none of which is guaranteed.

Gase hinted last week that Osemele was starting break down physically. He also had been dealing with a knee issue.

"When you get a veteran offensive lineman and they get banged up a little bit, it's not easy to come back and stay on the field," Gase said. "He has played a lot of football."

Osemele has played 96 games - four seasons with the Baltimore Ravens, followed by three in Oakland, where he made the Pro Bowl in 2016 and 2017.

The NFL Network first reported the surgery.

In another roster move, the Jets signed free-agent safety Blake Countess, a source said. The former Philadelphia Eagles draft pick played with the Los Angeles Rams (2016-2018) and returned to the Eagles this season before being released in the preseason.