Rezwan Ali, 19, suffered a cardiac arrest in the kitchen after he was knifed three times to the chest and arm, including a four-inch wound to the heart which severed a major artery.
Rajan Natt is accused of murdering Mr Ali during the fight, which unfolded between two groups at a house in Willows Road, in Walsall, on January 14, 2018.
Both men had gone "to enjoy themselves", jurors heard, with Natt attending with his friends – and Mr Ali arriving later that evening to join his friends, after finishing a work shift.
It ended with Mr Ali staggering, mortally wounded, from a fight before he "bled to death", as 20-year-old Natt and his friends "immediately" fled, prosecutors said.
Opening the case at Birmingham Crown Court on Monday, James Curtis QC said: "The Crown say the stabbing was a result of temper being lost in an escalating altercation between two separate group of friends.
"It started for no reason.
"It became a fist fight, then got out of control causing the senseless and tragic loss of a person's life."
Mr Curtis said what had started as a party for about 10 people, advertised on social media, ballooned, with up to 60 people attending.
He added: "Inevitably there were groups of friends who knew each other, and groups who didn't.
"As you know, it's a fact of life, tragically, when drink flows people start to bump each other in a crowded place. Perhaps particularly when they're male.
"Things can go wrong, things can get heated, things can get taken entirely out of context and blown out of proportion.
"That is probably how it all tragically began - and tragically ended."
The trouble began when, earlier that night, two of Natt's male friends "seem to have been making a nuisance of themselves", said the Crown's barrister.
Mr Ali, who a post mortem found had very little alcohol and no drugs in his system, had not been part of the initial trouble. There was "no suggestion the defendant was joining in", either, jurors heard.
Mr Curtis added: "He [Natt] didn't come to anybody's attention before the stabbing took place."
As tensions mounted, both groups went into the back garden where a fight started.
Mr Curtis said: "The people who witnessed this fight got the impression it involved punching, nothing more.
"Some even described it as a clean fight, if such a thing exists. Sadly they were wrong. Very wrong.
"The prosecution say Rajan Natt was armed with a knife – and he used it."
Desperate attempts to save the victim, including by a nurse who lived next door, were in vain.
The Crown alleged Natt fled with his friends, before getting a taxi, accusing him of later phoning another party guest in a bid to secure an "alibi" which could place him away from the stabbing.
Prosecutors also claimed Natt first told police "I wasn't there" during the fight and had not touched the victim, saying instead he only saw Mr Ali staggering into the kitchen.
However, when officers found Natt's bloodstained top, the defendant then claimed the victim might have brushed past him, added the Crown's QC.
Mr Curtis added: "There would appear to be no sign of any of the others having blood on their clothes."
Natt, of Castle Street, West Bromwich, denies any wrongdoing, and the trial continues.