Officers were called to Woodchester Square after reports of a fight between two men on April 21 at around 4.20pm.
The 27-year-old victim had multiple stab wounds and was taken to a central London hospital where he was treated for multiple injuries including a collapsed lung.
He has since been discharged from hospital.
A 25-year-old man was arrested on suspicion of attempted murder on Sunday April 23 and has since been released under investigation.
A 23-year-old man was arrested the following day on suspicion of attempted murder and has been released on bail until mid-May.
The Met's Organised Crime Command is investigating the incident and appealing for information from members of the public.
DC Darren Barclay said: "This was a violent attack which left the victim with serious injuries. This happened in broad daylight in an area overlooked by residents, and we would urge anyone who saw what happened, or saw possible suspects in the area at the time, to contact police."
Witnesses and anyone with information is asked to call 020 7321 7647, or Crimestoppers on 0800 555 111 if you would prefer not to give your name. You can also tweet @MetCC.
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