Emile Smith Rowe appeared to suffer an injury during Arsenal's post-match warm-down at Old Trafford, as the Gunners were beaten 3-1 by Manchester United on Sunday.
New Red Devils signing Antony stunned Arsenal with a debut goal in the first-half before Marcus Rashford struck twice in the second to fire United back ahead following Bukayo Saka's 60th-minute equaliser.
As Mikel Arteta's side hunted a pathway back into the contest, Smith Rowe was called upon to replace playmaker Martin Odegaard, making his fourth substitute appearance of the season.
And it seems the league leaders' trip to Manchester went from bad to worse during the warm-down, as their attacking midfielder looked to pull up with an injury.
As reported by The Athletic's David Ornstein, Smith Rowe looked to be in some distress during the substitutes' post-match session, which prompted Arsenal assistant coach Carlos Cuesta to accompany him back to the dressing room.
A setback would see the 22-year-old join midfield trio Thomas Partey, Mohamed Elneny and Reiss Nelson on the Gunners' injury list.
Despite featuring in 33 of 38 Premier League matches last campaign, Smith Rowe has yet to start under Arteta this season, with the Spaniard favouring an attacking midfield of Martin Odegaard, Gabriel Martinelli and Saka behind marquee summer signing Gabriel Jesus.
Arsenal kept hold of top spot despite suffering defeat at Old Trafford, as Manchester City failed to win all three points against Aston Villa on Saturday.
The Gunners take on Everton at the Emirates next weekend following their first Europa League clash against Zurich on Thursday.