Arsenal are assessing striker Kai Havertz after he suffered a muscle injury on the team's Dubai training camp.
There are fears that the 25-year-old has torn his hamstring and could miss the rest of the season.
The Athletic have reported that it is unclear if he will need surgery but report that his season is likely to be over, external.
The BBC has not yet verified these details and Arsenal have not released any statement.
Manager Mikel Arteta will be asked about the extent of the injury at Friday's news conference before his side take on Leicester City on Saturday.