Graham Potter broke ‘unwritten rule’ by substituting Aubameyang in Chelsea’s defeat to Man City

PIERRE-EMERICK AUBAMEYANG is "done" at Chelsea after Graham Potter broke an "unwritten rule" during their 1-0 defeat to Manchester City, Paul Merson has claimed.

The former Arsenal forward, 33, replaced Raheem Sterling in the fifth minute of the clash at Stamford Bridge on Thursday after the England international picked up an injury.

Then midway through the second half, after Riyad Mahrez had given the visitors the lead, Potter brought Aubameyang off and replaced him with youngster Omari Hutchinson.

The ";subbing a sub" move is something rarely seen at the top level of the game.

And former Arsenal midfielder Merson, 54, feels it showed that Aubameyang is finished at Chelsea.

Speaking to , he said: "As soon as you are sub-subbing a 30-something player, I think that is probably the end.

"Maybe you can get away with it with a younger player, but in football it's one of those unwritten rules. It's a don't-do.

"But Potter did it with him at 33, and, for me, I think he's done."

Aubameyang only joined the Blues from Barcelona in the summer on a two-year deal, with Chelsea paying £12million for his services.

He has scored just three goals in 15 appearances since returning to England.

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And Gabon's all-time top scorer has failed to hit the back of the net in any of his last 10 games for the club - a run which stretches back to October.

Aubameyang is also yet to start since the World Cup break, with Potter preferring to go with Kai Havertz as the focal point of his attack.

Chelsea are being linked with other forward options in the January window, with a deal for Atletico Madrid's Joao Felix closing in and Borussia Monchengladbach's Marcus Thuram also linked with a move.