A male model was warned that "violence wasn't a solution" before engaging in a fatal pre-arranged fight with another model.
Harry Uzoka, 25, died in west London after being stabbed in a row over a girl on 11 January, a court heard.
George Koh, who is accused of killing him, was a "big fan" of Mr Uzoka before his admiration "turned to contempt", the Old Bailey was told.
Mr Koh, 24, of York Way, Camden, denies murder.
The relationship between Mr Koh and Mr Uzoka is said to have deteriorated after French model Annecetta Lafon arrived in London at the end of December last year.
During a date at a hotel, Mr Koh told her he had slept with Mr Uzoka's girlfriend Ruby Campbell - also a model.
Ms Lafon, who describes herself as a good friend of Mr Uzoka's, later told him about Mr Koh's claim but said Mr Uzoka was "not surprised" and even laughed at the revelation, the court heard.
Mr Uzoka told her Mr Koh had made claims like this before and was a "big fan" of him, she said.
But the dispute escalated in a series of phone calls and messages on social media, and Ms Lafon said she knew Mr Uzoka was "angry".
"He told me he would try to meet up with George [Koh] and fix him, and I said that violence wasn't a solution," she told the court.
Giving evidence on day two of the trial, Ms Lafon said Mr Uzoka was annoyed by the less successful Mr Koh, who some said looked like him, because he tried to copy him and make contact with his friends.
Mr Uzoka ignored her warning and recruited his flatmate Adrian Harper to fight Mr Koh and his friends Merse Dikanda and Jonathan Okigbo in Ollgar Road, Shepherds Bush.
But while Mr Uzoka and his companion came armed with dumbbell bars, Mr Koh's group took at least three knives, including a machete, the court heard. Both ran off when realised they were confronted with knives, but only Mr Harper got away.
The jury was told Mr Koh had pleaded guilty to two charges of possessing a knife.
Mr Okigbo, from Camden in north London, denies murder.
Mr Dikanda, of no fixed address, denies murder, possessing a machete on 11 January and possessing a knife on 25 January.
The trial continues.