Berlin - German police said on Monday they had arrested a 30-year-old Schalke 04 fan in connection with an alleged assault on a Manchester City supporter after the English club's Champions League win there last week.
Police in Gelsenkirchen said that the man, a member of Schalke's hardcore "Hugos" fan group, is suspected of punching a 32-year-old male City fan near the away fans section at the Bundesliga club's Veltins Arena on Wednesday.
The Premier League club's supporter suffered a "massive traumatic brain injury" after falling, police said.
He was rushed to a nearby hospital where his condition is described as "critical".
The 3-2 victory in the first leg of the last-16 tie leaves the Pep Guardiola's side firm favourites to progress to the quarter-finals with the return in Manchester on March 12.