By Julien Pretot
FLORENCE, Italy (Reuters) - A brutal burst of acceleration helped Dutchwoman Marianne Vos to crush her rivals yet again to retain her cycling road race world title in awe-inspiring fashion on Saturday.
The Olympic champion made her move on the steep ramp on the Via Salviati and never looked back, widening the gap with her rivals in the final four kilometers.
Swede Emma Johansson took second place after outsprinting Italian Rossella Ratto.
"It is hard to win one title but to defend one is really tough," said Vos, who was the overwhelming favorite going into the 140-km race.
"The Italians made it a very tough race... I was not too confident in the last lap but on the steep climb I saw an opportunity."
The Italian team, with double world champion Giorgia Bronzini, were out to isolate Vos, but she never looked troubled, having Anna van der Breggen to thank after her team mate protected her all day.
"She has been in fine form all season and she was the one we wanted to have in the finale to keep it together," a beaming Vos told a news conference.
"She was here to react to every move and I could stay quiet."
In the last of five 16.6-km laps, Vos responded to Johansson's acceleration and left no chance for her rivals.
Johansson and Ratto chased but quickly realized they were no match for Vos, who now has 13 cycling gold medals from world championships and Olympic Games.
"At some point we came close but it was too late," said Johansson.
It was the 26-year-old Vos's eighth consecutive world road race podium after she won the title in 2006 before taking second place five years in a row.
(Editing by Clare Fallon)