Police are appealing for information about the "needless" assault. The43-year-old man suffered a bleed on the brain, a broken jaw, eye damage and severe bruising.
Couple viciously attacked after confronting man urinating in the street
His 34-year-old partner, meanwhile, had hair pulled out and had bruising after being thrown to the ground.
They had been walking along Fairfax Road in Swiss Cottage when they challenged the man for urinating in the street.
Three further people, two males and a female, then jumped from a nearby parked car and the two males began assaulting the couple.
It happened at about 1.15am on June 10.
Launching an appeal on Monday, with stills of two suspects, Det Con Angela Greaves, said: “I am keen to identify and apprehend those responsible for this needlessly vicious attack on a couple making their way home after a night out.
“I urge anyone who can put a name to the faces of the men pictured to call without delay. Any information provided will be treated in the strictest confidence.”
Anyone with information is asked to call police on101, quoting reference CAD634/June 10, or Crimestoppers anonymously on 0800 555 111