Pre-race favourite Bradley Wiggins endured another difficult day on a rain-lashed ninth stage of the Giro d'Italia although defending champion Ryder Hesjedal suffered most, dropping to 11th overall.

Russia's Maxim Belkov took the stage win but Wiggins, who crashed on a descent on Friday, remained fourth overall, one minute and 16 seconds behind leader Vincenzo Nibali despite for a time losing contact with the Italian and the other contenders on a technical downhill section about 55 km from Sunday's stage finish in Firenze.

"When it comes to descents [Wiggin's has] now got some kind of mental block - Giovanni Visconti

Following a 20-km chase by Wiggins' Sky team, the 2012 Tour de France winner managed to regain contact with the main group.

"I was racing right behind him," Italian rider Giovanni Visconti told reporters. "I could see he was handling the descents very badly. I think when it comes to descents he's now got some kind of mental block."

However, Team Sky principal Dave Brailsford said Wiggins's apparent caution on the downhill sections was never a concern.

"It was always going to come back," he told reporters.

"Bradley took it a bit cautiously on that descent and then obviously was confident his team mates would help him regain contact. There was never a problem."

Canadian Hesjedal had been sixth overall going into the stage through the hills around Firenze.

Hesjedal dropped back on the short climb of Fiesole close to the finish and lost 66 seconds on the other overall favourites.

As the race reaches its first rest day on Monday, Nibali leads by 29 seconds from Cadel Evans of Australia, with the Netherlands' Robert Gesink third at 1:15, while Hesjedal trails the leader by 3:11.

"Riders might seem otherwise but they're not machines", Charly Wegelius, Hesjedal's team sports director at Garmin-Sharp told Reuters.

"He's not sick, but it could have been a combination of the rain and the cold today and the efforts of yesterday's time trial all coming together.

"I was cramping so badly in the last few kilometres" - Maxim Belkov

"He really went deep yesterday and this could be the consequences of that."

Ahead of the favourites, Belkov secured the first win of his career aged 28 when he completed a 140-km breakaway through hilly terrain 44 seconds ahead of Colombians Carlos Betancur and Jarlinson Pantano.

"I had no idea I was going to get this win, I was cramping so badly in the last few kilometres and the main group was coming back so fast," said Belkov, whose victory was the second for Russian squad Katusha in the Giro this year.

"I'm better known as a time triallist, but I decided to go easy yesterday because that way I would be a lot stronger for today.

"Better first today in a hilly stage than 20th in yesterday's time trial."

After Monday's rest day, the Giro hits the mountains with the race's first major summit finish on Tuesday at Altopiano di Montasio in north-east Italy.

The Giro finishes on 26 May in Brescia.