A key witness in the A$AP Rocky assault trial in Sweden has withdrawn her claim that she saw the rapper and his guards hitting a man with a bottle.

The Fashion Killa hitmaker, real name Rakim Mayers, is facing two years in jail over allegations he and two members of his entourage attacked 19-year-old Mustafa Jafari on 30 June.

A young woman and her friend who witnessed the incident gave evidence in court in Stockholm anonymously via video link on Friday. The woman told the court that she didn't actually see the American rapper or his team hitting a man with a bottle, revising testimony she gave to police.

She said that although she had seen one of Rocky's friends holding a bottle, she only heard glass breaking and didn't actually see how this happened.

According to a reporter from website High Snobiety, her friend also replied "no" when asked by Jafari's lawyer Marcus Stromberg if she remembered actually seeing Jafari being hit with the bottle. She explained the alleged victim had said he had been hit but she "didn't actually see it".

Whether or not the teenager was hit with the bottle is a key point of contention in the trial, as the witness initially told the police this was the case.

Jafari's friend also gave evidence on Friday, claiming his pal was beaten badly during the altercation.

On Thursday, Rocky told the court that he did throw the alleged victim to the ground and punched and kicked him, saying the teenager had attacked his bodyguard. He denied hitting him with a bottle.

He and his companions pleaded not guilty at the start of the trial on Tuesday, claiming they had acted in self-defence.

Rocky's detention has sparked an outcry in the U.S. and, after Rocky was charged last week, and U.S. President Donald Trump asked Sweden's Prime Minister Stefan Lofven to help free the hip-hop star, a plea he declined, citing the independence of his country's judiciary.

Testimony in the trial is expected to wrap up on Friday.