SPA (AFP) - World championship leader Nico Rosberg secured his fourth Formula One pole position in succession on Saturday when he topped the times ahead of his Mercedes team-mate Lewis Hamilton in a tense and wet qualifying session for Sunday's Belgian Grand Prix.

The 29-year-old German clocked a best lap of two minutes and 5.698 seconds to outpace his British partner in treacherous and capricious conditions at the sprawling 7.004-km circuit in the forests of the Belgian Ardennes.

Hamilton struggled with his brakes and handling in the slippery conditions, but will start alongside Rosberg on the front row as he seeks to trim his 11 points lead in the drivers' championship with eight races remaining.

Behind the two Mercedes, defending four-time champion Sebastian Vettel of Germany was third fastest for Red Bull ahead of Spain's former two-time champion Fernando Alonso of Ferrari and fifth placed Australian Daniel Ricciardo in the second Red Bull.