A Chinese rugby player broke a student's eye socket when he called him a "chink" in a student bar, a court heard.
Sidney Chan, 20, is accused of kicking Stephen Kent in the face twice.
He claims the alleged victim abused him when they left the bar at London's prestigious Imperial College.
Prosecutor Paul Fairley suggested Chan "provoked" Kent by making a comment about his 1980s-style mullet haircut.
But Chan said: "I never said anything about his hair. He called me a chink.
"He started throwing punches at me after he fell to the ground after I had pushed him," said Chan.
"He quickly got back up and he charged at my group and started throwing punches at me."
CCTV showed Chan's friends trying to restrain him during the fracas - but he managed to break free to confront Kent again.
Prosecutor Paul Fairley said: "Why, given your account that you were frightened and thought that you were being assaulted, why did you seem so eager to get back into the fray and engage Mr Kent?"
He replied: "Because he was persisting to get back up and continue the fight.
"I guess at that point I was pretty angry and I wanted to make sure that he stops fighting me."
Fairley said: "You had completely lost your head, that fact that the member of your group was having to lift you forcefully off the ground to get you to move in the direction that everyone else was moving."
CCTV footage shows Kent seen falling to the floor, but the view of his body is obscured by a parked car as Chan runs by him twice.
Prosecutors claim this is the moment he swung the two kicks into his head and left him unconscious.
"You run behind the car then you turn and then run back in the direction you have just come from," said Fairley.
"The truth is Mr Chan isn't it, that you know as well as anyone that someone who is on the ground, there's no justification for kicking is there?"
A lorry driver stopped his vehicle in the middle of the road and got out to check on Kent.
Fairley said: "He could see straight away that his face was puffed up like a balloon, or words to that effect."
The assault left the Kingston University student with a fractured nose and eye socket and a heavy concussion.
Chan, who was studying at Imperial College, denies one count of wounding with intent.
He said: "All I wanted him to do was leave us alone, stop following us, and stop fighting me, and stop harassing my friends."
The trial continues.