Bukayo Saka will be sidelined for "many weeks" after suffering a hamstring injury in Arsenal's 5-1 win at Crystal Palace, manager Mikel Arteta said Monday.
Asked at a press conference about the 23-year-old England international's condition, Arteta said: "It is not looking good. He will be out for many weeks."
Saka was filmed leaving Selhurst Park on crutches on Saturday, souring what had been a comprehensive second win over the Eagles in four days.
Arteta said after the match: "He felt something in his hamstring. He couldn't continue. He will have to be assessed, so I'm pretty worried about that one."
He also revealed on Monday that Raheem Sterling had injured his knee and would be out for many weeks.
Arteta was asked if there was a fear Saka would not return before the end of the season.
"No (there's no fear)," he said. "I'm very optimistic he'll be back before the end of the season."
The Spaniard said it was part of the "development of a player".
"It could have been much worse. It could have been something else that can take you out for a year," he said.
"It's how you react to that, how you overcome that situation and it's a great learning process for him as well.
"It is what it is. He's injured, we cannot change it. We're going to use this time now to help him."
Saka is crucial cog in Arsenal's attack, scoring five Premier League goals and providing 10 assists this season, and his absence will be keenly felt.
Arteta said he was "putting some ideas together" about how to cope in the winger's absence.
"We went through the period with Martin (Odegaard) and the period with five, six defenders missing," he said. "We're taking it with positive energy."
Arsenal, who have finished as Premier League runners-up over the past two seasons, host relegation-threatened Ipswich on Friday.
The Gunners are third in the Premier League table, six points behind leaders Liverpool having played a game more.