The match was briefly halted after Williams drew attention to alleged racist sounds coming from the Estadio Civitas Metropolitano crowd.
Paris Saint-Germain squandered the chance to secure another Ligue 1 title on Saturday after playing out a 3-3 draw at home to struggling Le Havre in their last game before facing Borussia Dortmund in the Champions League semi-finals.Le Havre, who had won just one of their last 12 Ligue 1 games, stunned the home crowd on a rain-sodden evening by going ahead in the 19th minute.
Harry Kane scored twice for Bayern Munich.