Ricciardo - who won his last race in Hungary - notched up his third race victory of the season at Spa, while Rosberg finished second to extend his championship lead over Mercedes teammate Lewis Hamilton to 29 points.

Hamilton overtook pole-sitter Rosberg at the very beginning, but had his hopes dashed when the two made contact on the second lap. As Rosberg tried to retake the lead from his teammate, he slashed Hamilton's rear tire with his front wing - meaning the Briton had to retire five laps before the end of the race.

"Nico hit me, Nico hit me!" Hamilton was heard exclaiming in astonishment on the team radio.

The early withdrawal seriously dented Hamilton's title hopes, with seven of this season's 19 races remaining.

Rosberg, meanwhile, came in 3.3 seconds behind Ricciardo, who climbed from fifth to eventually take the lead.

"When you are leading the first thing is - you hope everything holds together," Ricciardo told the BBC after the race. "Mechanically, you hope everything gets you to the finish line but certainly when you are in the lead the checkered flag can't come soon enough."

Finland's Valtteri Bottas claimed third spot for Williams, with Ferrari's Kimi Raikkonen in fourth and German four-time champion, Sebastian Vettel, placing fifth.

rc/glb (AFP, AP, Reuters)