Two “out of control” dogs – believed to be Staffordshire bull terriers – locked onto each other at the Fountain Road Recreation Ground in Tooting.
The struggle lasted nearly five minutes as the owners repeatedly attempted to get their dogs under control, before one of the men collapsed and the other man led one of the dogs away.
The footage was captured by local resident, Kevin Kyle, who overheard the commotion from his house at 11.50am on April 28.
Kevin said: “The one gentlemen has ended up seriously injured.
“People were shouting to call the police but they were were saying ‘no’ as they ‘don’t want their dogs to be locked up’.”