Atletico Madrid striker Diego Costa has been applauded for his quick response as Arsenal defender Laurent Koscielny suffered a nasty-looking Achilles injury.

The 29-year-old striker was playing in his first game against Arsenal since last year's FA Cup final after leaving Chelsea in January.

Costa was the closest player to Koscielny when the Arsenal captain caught his studs in the turf before collapsing in agony, clutching the back of his right ankle.

The Spanish striker immediately urged his Atletico Madrid teammates to put the ball out of play to allow the defender to receive treatment.

Costa frantically waved on Arsenal's medical staff, indicating the severity of the injury.