Zlatan Ibrahimovic is unlikely to play again this season after suffering a serious knee injury during Manchester United's win against Anderlecht in the quarter-finals of the UEFA Europa League.

Boss Jose Mourinho said immediately after Friday's second leg — which United won 2-1 in extra-time to progress to the semi-finals — that the injury looked "bad" and the Swede faces an extended spell on the sidelines.

Ibrahimovic appeared to jar his knee when he landed awkwardly after making an aerial challenge and hobbled down the Old Trafford tunnel with the help of a member of the club's medical staff.

A United statement released on Saturday said Ibrahimovic and Marcos Rojo, who was also injured against Anderlecht, suffered "significant knee ligament damage" and will require further assessments in the coming days.

The 35-year-old has scored 28 goals in all competitions since signing for United on a free transfer from Paris Saint-Germain last July. He initially agreed a 12-month deal, with the option of an additional year. 

Ibrahimovic has not formally penned an extended contract, but has hinted it will happen, provided this injury doesn't end his career early.

"Estimations of time to full recovery will only be possible once definitive treatment plans have been decided after these consultations," United's statement read.