Manchester City have suffered a major setback before their trip to Chelsea on Saturday after the club confirmed Benjamin Mendy has sustained a serious knee injury that leaves his chances of returning this season remote.

After tests in Barcelona, it emerged that Mendy ruptured the anterior cruciate ligament in his right knee, the injury coming in a tackle with Andros Townsend in the first half of City’s 5-0 win against Crystal Palace last weekend.

A statement from City said: “Manchester City FC can confirm that Benjamin Mendy has ruptured the anterior cruciate ligament in his right knee. After initial tests in Manchester at the start of the week, Benjamin travelled to Barcelona to see a specialist doctor, where further examinations of the knee today confirmed the extent of the injury.

“Benjamin will undergo surgery [Friday] in Barcelona, and everyone at the club wishes him a speedy recovery. Mancity.com will bring you regular updates regarding his rehabilitation.”

Mendy tweeted: “Bad news guys. I will be joining Injury FC on loan for a couple months with ruptured ACL but will be back soon and stronger hopefully.”

The prospect of losing Mendy for the rest of the season severely weakens Pep Guardiola’s strategy as the left-back was a key part of his summer squad rebuild, with City paying £52m to Monaco for him. Before the injury, Mendy’s ability to attack at pace along the flank, coupled with a dangerous delivery, had immediately made City a more potent proposition than last term.

City are the Premier League leaders and have won eight out of nine in all competitions with Mendy featuring in five of the victories before being forced off after 29 minutes against Palace.

Last season City lost both the home and away league fixtures against Chelsea, who became Premier League champions for a fifth time, while City finished third.

Guardiola’s hope is that on Saturday he can take the team to Chelsea for the late game and lay down a marker that City are serious title challengers. That aim has been dented by Mendy’s injury and Guardiola’s problems in defence are compounded by Vincent Kompany having again been ruled out with a calf injury.