Kyle Walker was absent from Manchester City's open training session on Tuesday ahead of the Champions League final.
City head to Istanbul to face Inter Milan at the Ataturk Olympic Stadium on Saturday, aiming to become the first side since arch-rivals Manchester United in 1998-99 to win a historic Treble.
They are fresh off lifting the FA Cup after beating United 2-1 at the weekend, with Ilkay Gundogan's two goals enough to settle the tie.
But, ahead of their final assignment of the season, Kyle Walker wasn't present for their training session at the City Football Academy on Tuesday afternoon - which was open to media - in a worrying sign for Pep Guardiola's side.