Thought he played very well, apart from that daft f*ck up near our penalty box where he tried to be too clever and play his way out of a tight situation and lost the ball to Barcelona's midfield player, (especially because he had the option of passing to his left at the time I think), that was a potentially dangerous situation for the team, which was easily avoidable.
I think this is where Pep needs to coach Stones a bit more, to not be so cocky and think he can play his way out of all situations, sometimes a simple pass to a team mate will do.