The Belgian forward, who has produced five goals and five assists in all competitions this season, left the pitch shortly before half-time on Wednesday with discomfort in his left leg.

He received treatment from Arsenal's medical team before speaking briefly with Mikel Arteta and heading straight down the tunnel.

Arteta admitted after the 3-1 victory that the extent of the injury was still unclear. "With Leo, we don't know the extent of his injury," the manager said. "He said he felt something and we didn't want to take any risk."

The injury comes at a difficult time for Arsenal, who remain top of both the Premier League and their Champions League group but continue to deal with a long list of absentees. Viktor Gyokeres, Kai Havertz, Gabriel Jesus and centre-back Gabriel Magalhaes all remain out, while Trossard now joins them in the treatment room.

There were positives for Arsenal on the night. Noni Madueke returned from a long lay-off to replace Trossard and scored Arsenal's second goal after meeting a cross from Riccardo Calafiori. Gabriel Martinelli also came back from injury to score the third, while captain Martin Odegaard made a late cameo.

Madueke described the performance as a significant personal milestone. "I had a long injury, it was difficult, but today I made up for it," he told the club's website. "It was a Champions League night, so it was perfect to get my first goal for the club and for the win on top. It's a perfect night."

Arsenal travel to Stamford Bridge to face a Chelsea side who are second in the Premier League, seven points behind the leaders.

Arteta will provide another update on Friday, when he is expected to outline whether Trossard has a chance of featuring in one of Arsenal's biggest league games of the season.

Here is a summary of the current injury status for each Arsenal player mentioned:

Viktor Gyokeres: Remains out with a muscle-hamstring injury but is reportedly very close to a return and is expected back in the near future.
Kai Havertz: Is recovering from a knee procedure and is also targeting a return around the same time as Gyokeres.
Gabriel Jesus: Has been out for a longer period with an ACL injury but is back in full training and nearing a return to match action, potentially in early December.
Gabriel Magalhaes: Sustained a thigh injury on international duty and is expected to be out for "weeks".
Leandro Trossard: Is the most recent addition to the injury list, having been withdrawn as a precaution in the recent match against Bayern Munich due to discomfort, making him a major doubt for upcoming games.

Real Madrid boss Carlo Ancelotti rules out any more signings