Arsenal coach Mikel Arteta said he was “very concerned” about Bukayo Saka after the England winger was forced off injured against Crystal Palace.
Saka suffered a hamstring injury during the 5-1 win over Crystal Palace last Saturday, and was substituted in the 24th minute.
The 23-year-old was using crutches when he left Selhurst Park.
“He felt something in his hamstring and couldn’t continue,” Arteta said. “He will have to evaluate it. [I’m] Very worried about that.”
In response to a question about how long Saka might be absent, Arteta replied: “It is difficult. They tested him, but it is very difficult to determine how bad his condition is.”
Arteta added that fellow winger Raheem Sterling also suffered an injury, which ruled him out of Saturday’s match.
“We don’t know for how long,” he said. He added: “Losing players within 24 hours is not a good thing.
“Unfortunately, with the number of games we play and with this schedule, it doesn’t surprise me. But the team will react to that.”
Saka missed only two matches with Arsenal this season, after suffering a hamstring injury while playing for the England national team in October.
He also went off injured against Chelsea in November, ruling him out of the England match during the recent international break, but he was able to start in Arsenal’s next match against Nottingham Forest on 23 November.
Asked if this was Saka’s third hamstring injury, Arteta said: “I’m not sure if it’s the exact same injury, it’s in the same leg.
“I don’t know how big it is, but he already had two.”