Premiership footballer Anton Ferdinand admitted throwing the first punch in a confrontation outside a nightclub, Snaresbrook Crown Court has heard.
The 22-year-old West Ham player told police he feared the man was a "would be thief" and may have been armed.
Emile Walker claims he was hit once by Mr Ferdinand before being kicked and punched by up to 10 people outside Faces in Ilford, east London, in 2006.
Mr Ferdinand denies assault occasioning actual bodily harm and affray.
His co-accused Edward Dawkins, 28, of Beckton, east London, also denies similar charges.
In a statement, the footballer said as he left the club he became concerned about a group of men "hanging around" near the entrance.
He said: "I became apprehensive because one of the men began looking at me and my watch.
"Although it was insured I was worried in case the man might try to take it from me."
He explained that he had been mugged a year ago in Croydon when he had his mobile taken from him and a chain ripped from his neck.
"I found that incident frightening and I try now to avoid having to go through that again," he said.
Ferdinand said when the man threatened to kill his friend he became concerned that he may be armed.
He said: "For all I knew he had a knife. It worries me people who are prepared to start a fight do not do so without carrying a weapon."
When asked who threw the first punch Ferdinand, of Grove Park Road, Mottingham, south-east London, admitted he did.