Trouble broke out in the centre of Madrid tonight, when police tried to move dozens of high-spirited Schalke supporters off the street and herd them into a bar. One fan supposedly threw beer over the officers who then beat him before arresting him. One other travelling supporter was also arrested.Shalke play Real Madrid in the Bernabéu tomorrow night in the round of 16 of the Champions League, trailing 2-0 from the first leg.