A 20-year-old who was assaulted in Uxbridge High Street during the early hours of last Tuesday (August 2) remains in hospital more than a week later.
Police said they were called that morning at 3.49am to reports of a stabbing in the town centre.
Officers did not find anyone injured at the location but later discovered that a man had attended a west London hospital with stab wounds.
The man was transferred to a central London hospital, where he remains in a stable condition.
Two men aged 20 and 22 were arrested close to the scene , and a third man aged 20 was later arrested after handing himself in at a west London police station.
All three men were arrested on suspicion of attempted murder and have been bailed to return to police early next month.
Detective Sergeant Wendy Bassett, of Hillingdon CID, said: "This was a devastating attack on a young man who could have well been killed.
"If you were there or have information on what took place, please contact on 0208 246 1422 or Crimestoppers anonymously on 0800 555 111."
The stabbing was part of a spate of knife attacks across west London which took place in the space of just over a week, including fatal attacks in Southall, Kilburn, Russell Square and Kingsbury.