A foreign student suffered a suspected fractured skull when he was attacked and left unconscious and bleeding in the street.
The 18-year-old language student, from Portugal, was found on a pavement in Brighton, bleeding from his mouth and ears.
He was taken to the Royal Sussex County Hospital, where he was undergoing a brain scan today.
It was not known whether his injuries were life threatening.
Police said they believed the student, thought to be staying with a host family in the city, had been involved in a row in the Honey Club, in Kings Road Arches, before the attack.
He was found shortly after 2am in Black Lion Street near the junction with Kings Road.
Police were guarding the scene this morning and an area stretching from Black Lion Street round the corner towards the entrance to the Thistle Hotel in Kings Road was taped off.
Forensic science experts were expected at the scene later.
Two men were in custody this morning, helping police with their inquiries.
Officers have appealed for witnesses.
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