LIEGE: German Andre Greipel of Team Columbia headed a four-man sprint to win the treacherous 225km fourth stage of the Tour of Spain from Venlo in the Netherlands to here on Tuesday.

Greipel beat Belgian Wouter Weylandt, and the German duo of Bert Grabsch and Marcel Sieberg to the line just moments after around 40 riders, including overall leader Fabian Cancellara of Switzerland, suffered a huge pile-up just 2km from the finish.

But Cancellara, of the Saxo Bank team, managed to retain the race leader's gold jersey in the overall standings, 6sec ahead of second-placed Kiwi Greg Henderson, who won Monday's third stage.

"It was an astonishing finish but that's the race," said Greipel.

On a wet road, several riders at the head of the peloton slipped coming into a roundabout taking with them many more, and leaving only six free to continue unmolested.

The stage had taken place under continuous rainy conditions and spills were commonplace throughout the day.

In the race, there was a breakaway by Dutchman Lars Boom, Uzbek Serguei Lagutin, Germany's Dominik Roels and Spaniard Javier Ramirez after 20km, the quartet building up a lead of 11 minutes.

But they were reeled back in 12km from the finishing line thanks largely to the determination of the sprinter-heavy teams, notably the QuickStep outfit of Tim Boonen, who lies fourth in the overall standings.

Boonen, however, was brought down in the final pile-up alongside Cancellara and Spain's Alejandro Valverde.

The fact that the incident took place less than 3km from the line meant that the riders involved in the crash were given the same time as the winner.

The fifth stage will start in the Spanish city of Taragona on Thursday, with the teams and riders moving on Wednesday to the spiritual home of La Vuelta after their detour into northern Europe that has seen the stages attended by hundreds of thousands of fans.