Cameron Carter-Vickers’ second season with Scottish Premiership leaders Celtic has come to an early end and the American defender isn’t expected to be back in action anytime soon.

Carter-Vickers is set to miss 3-4 months following knee surgery, a source close to the player confirmed to SBI. Carter-Vickers had been fighting through a knee injury during the second half of the season and was expected to head for surgery following Sunday’s Scottish Cup semifinal match, a source confirmed.

Celtic manager Ange Postecoglou ruled Carter-Vickers out of the club’s final six matches of the season, which includes a Scottish Cup Final vs. Inverness CT later this month. The USMNT defender’s final appearance of the season came on Sunday as Celtic edged Glasgow rivals Rangers 1-0 at Hampden Park on Sunday.

Carter-Vickers, 24, joined Celtic on a permanent transfer last summer and has been one of the top defenders in the Premiership this season. The former Tottenham centerback totaled 39 combined appearances for Celtic, helping the current league-leaders win the Scottish League Cup and stay alive for a domestic treble.

He also appeared in the UEFA Champions League for the first time in his career.

Carter-Vickers has totaled 83 combined appearances for Celtic over two seasons, which has helped him fight his way back into the USMNT picture. However, his recent knee injury will force him to miss the USMNT’s CONCACAF Nations League and Gold Cup involvement.

Celtic will clinch this season’s Premiership title on May 7 with a victory at Hearts.