Man, 22, quizzed over assault in Cardiff city centre
A 21-year-old man needed an emergency operation after suffering a serious head injury following an assault in Cardiff city centre on Sunday.
South Wales Police arrested a 22-year-old man at the scene following an incident on Greyfriars Road at 01:30 GMT near The Crockerton pub.
Police are appealing for witnesses, saying CCTV images show some people assisted the victim.
He is being treated at the city's University Hospital of Wales.
The 22-year-old has been in custody at Cardiff Bay Police Station since his arrest on suspicion of assault.
South Wales Police have asked witnesses to call Cardiff Bay Police Station on 029 2052 7231 or Crimestoppers, anonymously, on 0800 555 111.