The Los Angeles Rams’ defensive end Myles Garrett needs a knee operation which will sideline him for at least four weeks.
The reigning defensive player of the year joined the Rams from the Cleveland Browns in the summer in one of the biggest trades in NFL history.
The 30-year-old made his Rams debut in their season-opening game against the San Francisco 49ers last week as the Super Bowl favourites suffered a 27-7 defeat in Australia.
The two-time defensive player of the year missed most of training camp with a knee problem but after the game it became clear he would need minor surgery.
The Rams have placed Garrett on their injured reserve (IR) list, which means he must miss at least four games.
“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, 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.”
The Rams’ defence has also been boosted by three-time defensive player of the year Aaron Donald coming out of retirement.
But the 35-year-old did not travel to Australia and coach McVay said the Rams are yet to decide if he will play next week against the New York Giants.
Garrett broke the NFL single-season record with 23 sacks last season but against the 49ers he failed to register a tackle for just the fourth time in his career.
Following the game, 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.”