A Spanish cycling armada is threatening to spoil Dutch hopes of securing an elusive victory in the Amstel Gold Race on Sunday.

The eighth race on the ProTour, and the fifth one-day classic of the series is the only Dutch race on the calendar apart from the Eindhoven time trial.

But the hosts’ annual expectation of seeing a tough challenge from the orange-clad home riders, most of whom ride for Rabobank, has taken on special significance this year.

Former winner Michael Boogerd will saddle up for his home race for the final time having announced in midweek that he will retire at the end of the 2007 season.

Boogerd, who will be 35 next month, turned pro in 1994 and over the past decade has dominated Dutch cycling along with the now-retired Erik Dekker, winning stages in the Tour de France as well as finishing fifth overall in 1998.

"I want to finish this season in style, starting on Sunday," warned Boogerd, who last won at Amstel in 1999 and has since appeared on the podium a remarkable, but agonizing, seven times.

Statistically, Amstel has the most climbs of any race on the European calendar.

And while each is not too long or difficult, the total of 31 climbs means Amstel is best suited to those who at least have the legs to manage that kind of repetitive effort.

Given the Spanish contingent's recent performances at the Tour of the Basque country, where the hills are steeper, longer and much more punishing, Boogerd will have to be vigilant throughout the 252.km race.

Spanish ace Alejandro Valverde is a big favorite, having been one of the protagonists in the Basque country where he finished fifth overall.

Valverde could be trying to set up a winning streak beginning Sunday and ending with victory at Liege-Bastogne-Liege in two weeks' time.

The Spaniard won the 2006 edition of Liege-Bastogne-Liege, one of the most prestigious scalps to claim because it is the oldest one-day classic in existence.

Days before that victory, Valverde won Fleche Wallonne, which will be raced this Wednesday. Ahead of his bid to add Amstel to his list, the Caisse d'Epargne ace will in turn be keeping a close eye on at least two of his compatriots.

Saunier Duval pair Juan Jose Cobo, 26, and Jose Angel Gomez Marchante danced with surprising ease over the tough hills in the Basque country where Cobo took the overall win and two stages.

Italian Riccardo Ricco, 23, is another contender.

Like Cobo, he has stormed his way into the European peloton and his climbing prowess at the Tirreno-Adriatico stage race, then at Milan-San Remo, means he can throw his hat into the Amstel ring.

CSC's defending champion Frank Schleck of Luxemburg, Euskaltel's Samuel Sanchez - another Basque Country performer - and Italian Danilo Di Luca will all be looking to finish triumphantly atop the final climb at Cauberg.

"I'm very close to prime condition," warned Di Luca, who rides for Liquigas.

All Dutch eyes meanwhile will be on Rabobank veteran Boogerd, known affectionately as "Boogie", who will have the unflinching support of Spanish team-mate and three-time world champion Oscar Freire.