Kieran Tierney was walking out of the shower when he suffered the serious knee injury which recently kept him out for several months, it has emerged.
The left back needed surgery after damaging knee cartilage towards the end of last season.
Tierney missed Arsenal’s final 10 matches, with Nuno Tavares and even Granit Xhaka deputising as Mikel Arteta’s side missed out on Champions League football.
The Scotland international initially suffered a problem in February before his knee ‘collapsed’ after training a few weeks later.