Newcastle United manager Steve McClaren has warned summer signing Aleksandar Mitrovic that he must learn to keep his emotions in check.
The Serbia international was shown a yellow card for a tackle on Swansea City's Neil Taylor soon after coming on during Saturday's meeting at the Liberty Stadium.
It comes just a week after an identical case on the opening weekend of the campaign, when Mitrovic lunged in on Southampton's Matt Targett.
"There was nothing in it, but there was a reaction from players and the crowd," McClaren told BBC Sport. "He's a physical player and we can't take that away from him.
"One thing we learned from Saturday, you've got to learn about emotional control. Referees need to be more aware - not be lenient, but allow the game to go on."
Mitrovic joined Newcastle from Anderlecht for a fee of £13m earlier this summer.
