The Mail on Sunday says substitute Adam was sent on at the start of the second half, with Stoke a goal down. He announced himself with an apparent stamp on Andre Schurrle's standing foot as they contested a 50-50 ball.
Referee Lee Probert did not punish the offence, but Schurrle received protracted treatment before being taken off after an hour.
Chelsea manager Jose Mourinho was unwilling to become involved in another controversy, saying: "I like aggressive football. I can't go inside a player's brains to find out if the intention was to hurt or not to hurt."
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