Australia's Mark Webber has won the showcase Monaco Grand Prix, making it an unprecedented six different winners in six formula one races so far this season.
Webber led a processional but nail-bitingly close race from pole position to chequered flag with the top three separated by less than a second at the finish.
Germany's Nico Rosberg was second and Fernando Alonso's third place for Ferrari has taken him three points clear at the top of the championship standings.
It was Webber's first win since Brazil at the end of last season, but it could be subject to a protest by other teams regarding the legality of his Red Bull's floor.
Alonso has 76 championship points, three clear of Webber and Sebastian Vettel who finished fourth in Monaco.
Schumacher, who had set the fastest time in qualifying but was slapped with a five place grid penalty carried over from Spain, retired after 64 laps.
Venezuelan Pastor Maldonado, the heroic winner in Spain, crashed out on the opening lap.