Arsenal's 2-1 victory against Fulham on Tuesday night was marred by injuries to defensive duo Gabriel and Jurrien Timber.
It proved a mixed night for the Gunners who saw Bukayo Saka mark his return from three months out with a hamstring injury by scoring — but also lost centre back Gabriel after just 16 minutes to a hamstring problem.
Arsenal secured victory — with Mikel Merino grabbing the other Gunners goal and Rodrigo Muniz netting Fulham's consolation — to close the gap on Premier League leaders to nine points.
But the injury to Gabriel is a seismic blow ahead of their Champions League quarter-final first-leg tie against Real Madrid next Tuesday at the Emirates.
Both he and Jurrien Timber, who has a knee concern, will be assessed on Wednesday.
‘Yes (there is concern) because he (Gabriel) never comes off,' said Arsenal manager Mikel Arteta.
'He felt something. We don't know how big it is.
‘Jurrien as well. He was already struggling very early in the game. He managed to continue, at some point he couldn't.'
Before the clash with Real Madrid, Arsenal travel to David Moyes' Everton for Saturday's lunchtime Premier League match.