Sebastian Vettel has reduced Lewis Hamilton's championship lead to 17 points after sealing a commanding victory in Belgium on Sunday.

Ferrari's Vettel passed pole-sitter Hamilton on the opening lap of the Spa-Francorchamps race before taking the chequered flag 11 seconds clear of his rival.

Unlike in the wet of qualifying 24 hours earlier, Hamilton's Mercedes was no match for Vettel, with Red Bull driver Max Verstappen completing the podium places.

Fernando Alonso was sent airborne over the Sauber of Charles Leclerc after Nico Hulkenberg crashed into the back of the Spaniard's McLaren at the opening bend.

But all three drivers walked away from the terrifying crash with Alonso suggesting the halo, the cockpit protection device controversially introduced this season, may have avoided serious injury to Leclerc.

Following back-to-back victories for Hamilton before the summer break, Vettel needed to stop the rot on Formula One's return to action here in the Ardennes forest.

On Saturday, Hamilton took advantage of a rain shower in qualifying to secure the front slot on the grid, but Vettel won the race by moving past his rival in the opening exchanges.

Hamilton held off Vettel at La Source but then, he was unable to stop the Ferrari car from sailing past on the ensuing Kemmel Straight.

Vettel came under pressure from Hamilton at Les Combes, but the Ferrari man held the racing line to retain the lead.