By Julien Pretot

LONDON (Reuters) - Since she won the 2006 title, Marianne Vos has always finished runner-up in the road world championships, but in Sunday's Olympic race, silver is just not going to be good enough for the Dutchwoman.

Vos won the 2008 Olympic and world points race event on the track and also has five cyclo-cross world titles, but on the road, she has had to accept silver every year since 2007.

This was not going to happen again, she warned after destroying the opposition in this month's Giro Donne, the women's version of the Giro d'Italia.

"It will be a tough race but I do not think I can be satisfied with silver or bronze," she said when asked about the 140-km race that begins and ends on The Mall in central London.

Vos, who was out of action in June after breaking her collarbone, hammered the field at the Giro Donne, winning five out of nine stages and notably outsprinted rival Emma Johansson twice with the Swede taking her revenge on the final day.

"Am I stronger than ever? Yes, I think I can say that," Vos added.

The rest of the field, however, will be extremely tough.

It includes Italy's double world champion Giorgia Bronzini, who has failed to shine while wearing the rainbow jersey and is keen to reverse that trend.

"I have built up a bit of anger to use in this race," Bronzini said.

"My rivals should be the usual ones, from Vos to (Ina) Teutenberg to (Nicole) Cooke, but that's not counting the outsiders, like Shelley Olds, who had not been included in the group of contenders for the win."

Beijing silver medalist Johansson will also be among the ones to watch closely, as well Germany's Teutenberg, who took the bronze medal at the world championships in Copenhagen last year.

The American and British teams will also be strong contenders.

The U.S. team boasts time trial Olympic champion Kristin Armstrong, 2008 time trial world champion Amber Neben and sprinter Olds, who also had a strong showing at the Giro Donne.

Britain will turn to Beijing champion Nicole Cooke, although Lizzie Armistead could come into contention if the race is decided on a sprint.

Armistead was the designated leader at the last world championships but failed to live up to expectations, triggering a public quarrel with Cooke, who has also failed to shine since her Olympic and world double four years ago.

"We have Lizzie and Nicole as the two main riders for the team," said British women's road coach Chris Newton.

"We are looking for results, whether it will be Lizzie or Nicole. We've got Nicole ...to use (and) she will be given (free) rein of attacking and riding from an aggressive point of view.

"If that succeeds, we're very happy for Nicole to go for glory and ride for that win."

(Editing by Greg Stutchbury)