SAN MARINO, April 25: German world champion Michael Schumacher won his fourth race out of four this season here on Sunday with a comfortable victory in the San Marino Grand Prix.

Schumacher led from the 11th lap onwards and finished well clear of Britain's Jenson Button (BAR) in second and Colombia's Juan Pablo Montoya (Williams) in third.

Button, who captured his first-ever pole position to general suprise on Saturday, made a perfect start from the front of the grid and built up a quick lead over runaway championship leader Schumacher.

But Schumacher, after holding off a tough challenge from Juan Pablo Montoya in his Williams, began to lap faster and was in Button's slipstream on the ninth lap when the BAR driver pulled into the pits for a fuel stop.

David Coulthard in a McLaren slid off at the first bend after colliding with Jarno Trulli's Renault and breaking his front wing. The Scot went into the pits for repairs and resumed from last place.

The second half of the race saw Schumacher steadily build up his lead over Button to over 20 seconds after making an third incident-free visit to the pits on the 46th lap.

He then eased up considerably to coast home. Button settled for second long before the finish and Montoya held off a late challenge from Fernano Alonso of Spain in a Renault to complete the podium.

Results: