SA man serious after one-punch attack

A man has had his lip re-sewn to his face and is recovering from a seizure following a one-punch attack in Adelaide on New Year's Eve.

Tristian Jarman, 21, was set upon by a group of about six men after an altercation in Glenelg, police say.

He remains in hospital in a serious but stable condition after he had a seizure and was found to be bleeding from the brain in three places, according to a family statement on Facebook.

They are appealing for any witnesses to the attack to come forward and believe the incident was filmed.

"In the meantime, we all appreciate the thoughts and prayers for my baby brother," Mr Jarman's sister wrote.