Boonen, who has already won a stage of this year's race, beat Italian Fillipo Pozzato and German rider Heinrich Haussler to the finish line, following a fast finish to what had been a very slow stage.

The riders in the race decided to ride the stage slower than usual as a protest to yesterday's stage, where there was a hill in the closing stages that was not reflected in the race itinerary andwhich took them all by surprise.

The overall average speed of the stage was just 34km per hour, way below the usual average for a race of these characteristics, which would be comfortably over 40km per hour.

Indeed it took the riders an hour to complete the first 15km of the day.

As a result, there is no change to the overall standing, where Spaniard Alberto Contador still has a lead of over a minute over American Levi Leipheimer, who also rides for his Astana team.

Contador, who didn't ride this summer's Tour of France, is aiming to win the three-week Vuelta for the first time in his career to add to the Tour of France he won in 2007 and the Giro de Italia (Tour of Italy) that he won this May.

Wednesday's stage between Zamoraand Valladolid and Thursday's ride between Valladolid and Las Rozas (just north of Madrid) are both relatively flat stages and unlikely to produce any changes among the race leaders.

The only chance either Leipheimer or third placed Carlos Sastre have therefore of beating Contador will be in Friday's mountain stage between Las Rozas and Segovia or in the final time trial, which is up the 1,870m high Puerto de Navacerrada.