The fight broke out in Walmer Road in Fratton last night at about 11pm.
When police arrived they found a 22-year-old man had been assaulted. He was taken to hospital and is still there.
A 24-year-old man from Southsea and an 18-year-old man from Portsmouth have been arrested on suspicion of grievous bodily harm with intent.
Woman, 44, whose large Dobermann dog mauled girl, 3, on Leigh Park street released back into neighbourhood by police
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An 18-year-old man from Havant has been arrested on suspicion of affray.
Anyone with information is asked to call 101 quoting 44190203759.