ASAP Rocky has pleaded not guilty to assault in Stockholm.
The US rapper, real name Rakim Mayers, is on trial accused of assaulting a 19-year-old Afghan refugee in the Swedish capital a month ago.
Two members of the 30-year-old's entourage are also on trial and have pleaded not guilty.
ASAP Rocky and the two other suspects, who've been held in prison after a fight that took place on 30 June, claim they were acting in self-defence.
Warning: There are images below showing bloody injuries to a person's body, which you may find upsetting
The trial - which is in its first day - was delayed starting due to the massive media and fan interest in the case.
There were issues getting in and out of the court and some fans had to be turned away from the public gallery as it quickly filled up.
The prosecution are going through a detailed 522-page preliminary report, which contains extensive photographs of injuries the alleged victim suffered.
The alleged victim, who is not being named by media, has claimed damages of roughly £12,000 (139,700 Swedish Krona).
They allege that ASAP Rocky used a weapon - claiming the injuries are consistent with the use of a bottle or a similar blunt object.
A lawyer for one of the rapper's co-defendants claims he has completely new evidence that he believes will ensure the trio are found not guilty of assault - but would not yet reveal what type of evidence it is.
It's expected that evidence will be shown to the court on Thursday.
Inside the courtroom
Maddy Savage, BBC News
Sat in the front row, ASAP Rocky has appeared really engaged throughout the hearing.
He's wearing a green T-shirt - a standard-issue uniform given to suspects detained in Sweden before a trial - and his braids are tied back off his face, so you can see the earpiece he's using to listen to a translation of the proceedings.
The document that's being presented to the court includes text messages from some of ASAP Rocky's friends, graphic photos of the alleged victim's injuries, and transcripts of conversations witnesses had with the police.
Photographs of the bottle allegedly used during the fight have also been shown.
ASAP Rocky's mum is in the front row in the gallery, where his supporters and media are sitting.
It's separated from the main courtroom via a glass screen. She's being mobbed by journalists as she enters and leaves the courthouse and looks unsettled by the attention.
Just before the court broke for lunch she shared a long hug with one of ASAP Rocky's other supporters in the gallery.
The trial is scheduled for Tuesday, Thursday and Friday - although it could finish before then.
Assault causing actual bodily harm carries a maximum prison sentence of two years in Sweden.
ASAP Rocky has been held in custody since 3 July following an alleged assault which took place on 30 June.
His imprisonment has attracted the attention of US President Donald Trump, who said he'd spoken to the Swedish Prime Minister after requests to intervene from Kanye West and his wife Kim Kardashian West.
The prosecutor in charge, Daniel Suneson, previously told Radio 1 Newsbeat he hadn't spoken to any White House representatives, or any representatives of the Swedish government, while investigating.
President Trump later demanded that Sweden "Give A$AP Rocky his FREEDOM".