England rugby star Danny Cipriani was swerving his Mercedes in both lanes before crashing into a taxi, a court heard.
Evidence was given by taxi driver Muhammind Quasim, whose taxi was hit by Cipriani's car, at the 28-year-old's drink driving trial at Westminster Magistrates' Court on Monday (April 18).
He described a heated row between him and the player, who had starred in England's win over Barbarians at Twickenham only hours earlier, after the crash on June 1 2015.
The witness, who was driving in Imperial Road, Fulham , at the time with a passenger in the front seat, said he saw the oncoming vehicle and began to slow down when he noticed it was swerving.
Mr Quasim said the Mercedes then hit his car, a Toyota, before Cipriani drove a little further and stopped.
The England rugby star arrived at court this morning - more video here
The taxi driver, whose passenger called the police, claims he then approached the vehicle. A dispute between them over who had caused the accident then broke out, the witness claimed.
The witness also claims he could smell the alcohol on the defendant's breath, adding that he was "aggressive and saying 'you hit my car'".
The witness added: "I could smell the bad smell from his mouth (alcohol).
"He could not speak properly and he was stuttering."
It is also claimed by the witness that he suffered injuries as a result of the crash.
Police arrived, breathalised Cipriani and then took him away.
He was charged after the test returned a reading of 67 microgrammes of alcohol in 100 millilitres of breath - almost double the legal limit of 35. He denies the charge .
Cipriani's legal team argue there were issues identifying the defendant and insist that the test was 'unduly delayed'.
The trial continues.