Stains found on a jacket belonging to Leeds footballer Lee Bowyer matched the blood of a student whose brother was beaten senseless in a street attack, a court has heard.
Home Office forensic scientist Mark Bates said the chance of the blood found on the cuff of the Prada leather jacket matching that of anyone other than Shahzad Najeib was one in a billion.
He said his findings indicated very strongly that Bowyer had come in direct contact with Shahzad Najeib after he received his injuries.
Shahzad Najeib, 21, has told the Hull Crown Court trial one of a group of men who were kicking and beating his brother Sarfraz, 20, as he lay on the ground in Leeds city centre last January broke away and punched him in the face.
Bowyer, team-mate Jonathan Woodgate, and reserve team striker Tony Hackworth, together with two other men, are alleged to have attacked Sarfraz Najeib, leaving him with a broken nose, cheekbone and leg and cuts to the head after a confrontation outside a city centre nightclub.
Mr Bates said: "The chance that someone else other than him would share the same profile is one in one billion - that is, one in a thousand million.
"In my opinion these findings provide very strong support for the view that Mr Bowyer had come in direct contact with Shahzad Najeib after he received his injuries rather than coming into contact with someone else stained with Shahzad Najeib's blood."
Mr Bates told Desmond de Silva QC, for Bowyer, scuff marks on the jacket could have been caused by Bowyer falling to the ground, which is what the footballer claimed happened in an interview with police.
Woodgate, 21, an England defender, of Middlesbrough, Bowyer, 24, of Leeds, Hackworth, 20, a reserve team striker, of Leeds, and Caveney and Paul Clifford, both 21, of Middlesbrough, deny causing grievous bodily harm with intent to Mr Najeib, of Rotherham, South Yorkshire. They also deny affray.
Woodgate, Caveney and Clifford, with Leeds United player Michael Duberry, 24, also plead not guilty to conspiring to pervert the course of justice after the attack. The trial continues.