A teenager was taken to hospital after police in the force helicopter saw him being beaten up from the air.
The 17-year-old is in a serious condition after he was attacked on Blackcarr Road in Baguley at 0245 BST.
Three men punched and kicked him before running off. Police on the ground were alerted and the teenager was taken to Wythenshawe Hospital.
Three men, aged between 22 and 25, were arrested on suspicion of assault and are being questioned by police.
Det Con Louise Moss, of Greater Manchester Police, said: "We are quite fortunate not to be dealing with an even more serious incident here.
"Thanks to the quick actions of our air crew and officers on the ground we managed to make three quick arrests.
"I want to reassure the victim, his family and the wider community that this will be thoroughly investigated."