A "rocket" shot from the star, Cristiano Ronaldo, left a security officer seriously injured in the head while standing behind, during warm - up drills before Manchester United's first Champions League game.

Footage went viral of Ronaldo, sitting on the floor to check on the security officer, who was lying on the ground surrounded by other security agents.

After checking on the security man's safety, Ronaldo returned to complete the warm-up, before launching his first Champions League game this season in front of the Swiss Yang Boys.

Ronaldo did not wait long, and he opened his team's championship goals after just 13 minutes, using an elaborate pass from his compatriot Bruno Fernández.