It looked like just before he was taken off, he squared up a defender then just lost the ball and hit the ground rubbing his leg. He could have been carrying the knock from earlier though I guess.
Thought he was a bit like the Gakpo of last season where he'd be on the periphery of games too much, just having Diaz switched there gave them more to worry about, although he was poor too. Just one game though, not many played well