By London correspondent Tony Hughes

Aaron Cresswell will be sidelined for up to four months with a knee injury, it was confirmed by West Ham on Monday evening.

The Hammers revealed on their official website the extent of the damage suffered by the 26-year-old in Saturday’s pre-season victory over German side Karlsruher.

The left-back was hurt in a challenge and will require an extended spell on the sidelines before he is fit to play again.

West Ham revealed that Cresswell had undergone a scan and will consult a specialist in central London early next week.

The medical team will then take a decision whether or not the defender requires surgery.

“Whatever course of action we decide to take, Aaron faces a period of rest, followed by treatment and rehabilitation and he will be out for a period of between three and four months,” the club’s head of medical and sports science Stijn Vandenbroucke told the West Ham website.

Vandenbroucke also gave an update on Manuel Lanzini, who suffered a knee injury in Argentina’s 2016 Rio Olympic Games warm-up fixture with Colombia at the weekend.

“We are in close contact with Manuel and the AFA (Argentine Football Association), who have started a late-release replacement procedure with the IOC (International Olympic Committee),” said Vandenbroucke.

“Until he has been assessed by the IOC, he cannot be replaced, but after this process has been completed we want him to return to England to be assessed by our own medical staff as soon as possible.”

An extended period on the sidelines for Cresswell could cause major problems for West Ham, with make-shift left-back Angelo Ogbonna the only senior replacement in the squad.

Cresswell was a key player last year in an outstanding season for West Ham, who defied the odds to finish seventh in the Premier League and guarantee European football for this campaign.

The former Ipswich man arrived in East London in 2014 and immediately made an impact, winning Hammer of the Year in his first season.

West Ham loaned out young left-back Stephen Hendrie to Blackburn Rovers last month and now look set to bring in a ready-made defender, rather than recall the Scottish Under-21 international.

In other West Ham team news, they will have to pay £14.3million if they want Swansea’s international star.