Los Angeles Rams outside linebacker Myles Garrett needs a knee operation which is expected to sideline him for at least four weeks.

Garrett joined the Rams from the Cleveland Browns in the summer in one of the biggest defensive trades in NFL history.

The two-time NFL defensive player of the year played in his side’s season-opening game against the San Francisco 49ers in Australia last week but the Super Bowl favourites suffered a 27-7 defeat.

“I don’t really [have a timeline] yet,” said Rams head coach Sean McVay.

“It’s all contingent upon [surgery]. You feel good about it. But I think it’d be unfair to him or really just without having the totality of all the information, to put any sort of timeline on it.

“We know that he’ll be available in four weeks potentially, so we’ll just take that a day at a time.”

Garrett broke the NFL single-season record with 23 sacks last season but did not manage a tackle in the defeat by the 49ers.

Following the match, Garrett said: “I’ve got to find a way to recover and get back to the player I know I can be and I’ve shown that I’ve been before.”