Millwall striker Aiden O’Brien will be out of action at the start of the season after rupturing his ankle ligaments.

The 21-year-old was taken off on a stretcher after 13 minutes of the 1-1 draw with AFC Wimbledon in the team’s friendly on Saturday, July 18.

He will now miss all on the Lions’ August fixtures.

Manager Neil Harris told : “We saw at the end of last season that Aiden is a player who is beginning to realise his huge potential.

“Naturally it is very disappointing, not just for me, but also for the boy himself.

“We hope it is just a minor set-back for Aiden and he can come back fitter and stronger.”

Forward Paris Cowan-Hall has returned to training but Millwall may still need backup with O’Brien out until September at least.