Arsenal manager Mikel Arteta says winger Bukayo Saka will miss “many weeks” with a hamstring injury.
The England attacker was forced off during Saturday’s 5-1 win against Crystal Palace and left Selhurst Park on crutches.
Saka, 23, has scored nine goals and provided 13 assists across 24 games in all competitions this season.
“It’s not looking good,” said Arteta. “He’s going to be out for many weeks.
“It’s a huge blow but it’s going to be a big exercise for us to overcome another challenge.”
Asked whether Saka had “torn” something in his hamstring, Arteta replied: “Yes. Probably there are ways to prevent the injury.
“There are a lot of factors. We are looking at everything and what we can do differently.”
Arteta added Saka was “gutted” and “really emotional” after discovering the severity of his injury.
The Spanish coach also confirmed that Raheem Sterling is set for a spell on the sidelines after sustaining a knee injury.
The Gunners next face Ipswich at Emirates Stadium in the league on 27 December (20:15 GMT kick-off).