A fight during a drinking game led to the stabbing of a man, allegedly at the hands of his flatmate, a court has heard.

When police entered a unit on Marion Street, Auburn, in the early hours of February 4 last year, 23-year-old Gongcheng Chen was already dead.

One of two stab wounds to his thigh had severed an artery and vein.

Prosecutors said the victim had been arguing with flatmate Chang Jie Wang during a party.

The argument was allegedly about Mr Chen's sister, who was also Wang's former girlfriend, who was in China at the time.

"The accused ... appeared to be the more aggressive of the two," prosecutor Giles Tabuteau said.

A couple who also lived at the unit, but were not attending the party, left the home when attempts to separate the two men failed.

Six people were initially at the party and had been taking part in a game, which involved people drinking from a cup according to the card they were dealt.

The jury was told Wang was heard threatening Mr Chen in a phone call to his ex-girlfriend Elva, during the course of the argument.

Elva was the leaseholder of the unit and previously lived there but the couple had broken up in November 2013.

The court was told in one phone call Wang asked Elva if she missed him.

"No. I'm coming back with my husband. I don't miss you," she said.

Wang then allegedly threatened Mr Chen.

"If anything happens to your brother, don't blame me," Wang allegedly said.

Wang has pleaded not guilty to murder.

The trial is expected to last three weeks.