Saliva found on the t-shirt of a victim allegedly involved in a fight with N-Dubz's Dappy has a "billion-to-one" DNA link to the rapper, a court has heard.
A trial at Guildford Crown Court was told that Dappy sparked a "mob attack" when he spat at two girls who refused to get into a car with him and two friends at a petrol station in the early hours of the morning.
The spit missed the girls but he then spat at another person, David Jenkins, who had stood up to defend them before becoming subject to the attack himself, the court heard.
Dappy, charged under his real name of Costadinos Contostavlos, swung a punch at him before Mr Jenkins put the rapper in a headlock, the trial was told.
Forensic scientist Carolyn Smith told the court that saliva linked to Dappy was detected on Mr Jenkins' t-shirt.
She said: "We estimated the probability of getting this DNA profile from another person who was unrelated to Mr Contostavlos as one in a billion."
Paul Greaney, defending Dappy, asked Ms Smith if the saliva could have been wiped on to the t-shirt sleeve as a result of the headlock.
She replied: "It could have been that way, there are numerous options."
Brian Stork, prosecuting, told the jury that Dappy, 25, pulled up in a car at the Shell garage in Woodbridge Road, Guildford, Surrey at about 3.30am on February 28 last year.
He and a friend, Kalonji Stewart, got out of the car along with a third man.
While Stewart went inside the shop Dappy began talking to the girls, Grace Cochran and Serena Burton, who were in a group sitting on the kerb outside.
Mr Stork alleged that Dappy tried to persuade the two girls to come with them in their car and when they refused he called the girls sluts, said one was ugly and then spat at them, but missed.
Mr Stork said that after Mr Jenkins was spat at, Dappy swung a punch at him and the violence "kicked off".
The incident then turned into a "mob-handed, utterly unlawful and aggressive attack", according to Mr Stork.
Dappy was joined by two other men, Kieran Vassell and Alfred Miller, who had arrived in a second Mercedes car with other unidentified men.
Mr Stork showed the jury CCTV footage, lasting just moments, from the garage.
It showed the men attacking Mr Jenkins and his two other friends, resulting in damaged teeth to Mr Jenkins and a fractured nose to another man. They then all got into cars and drove off.
Miller and Vassell are alleged to have used their feet and fists in the attack and Dappy is alleged to have got involved when he was released from the headlock.
Stewart also got involved but less so, the prosecution claims.
Taxi driver Tahir Jaffrey told the jury that he pulled on to the forecourt and saw a group fighting.
He described how he locked his car's doors because he did not want him or his fare-paying passenger to become inadvertently involved.
He said: "I do not want to see violence, I just called police when I saw it happen.
"I saw these three guys and all of a sudden people came out of their cars and began fighting.
"I do not know how this fighting started. It was very quick what I saw."
Dappy denies two counts of common assault on the two women, one of assault by beating, of Mr Jenkins, and one of affray.
He is charged alongside Vassell, 25, of Hammersmith, west London, and Stewart, 32, of Harborne, Birmingham, who are each charged with affray.
Miller, 28, of Brentford, west London, has pleaded guilty to affray and his case was adjourned for sentence at the end of the trial.
Mr Stork said Dappy told police when he was arrested that he was attacked, put in a headlock, his security came to help him and he then got straight into a car.
He denies spitting at anyone and said he cannot understand how his saliva came to be on Mr Jenkins' shirt.
The other men made prepared statements to officers and then gave "no comment" interviews.
The trial was adjourned until tomorrow.