Mercedes ruled out 'risky' one-stop

Sebastian Vettel lost third place on the penultimate lap at Spa when his right-rear tyre exploded on the Kemmel Straight as he tried to get to the end of the race with just one pitstop.

It was the second high-profile tyre failure of the weekend following a blowout suffered by Nico Rosberg in free practice, and Vettel slammed F1 tyre supplier Pirelli post-race.

Mercedes motorsport boss Toto Wolff said his team took a close look at the one-stop strategy before the race, and he understood why Ferrari took the gamble.

"We discussed it at length, the attempt of a one-stop like Ferrari," said Wolff.

"It took us a bit by surprise and I guess it took everyone else by surprise that they tried it.

"I understand why Ferrari did it because it was probably the only chance to end up on the podium.

"They attempted it but it was a risky strategy."

Sauber driver Felipe Nasr said it is important Pirelli is able to provide some detailed answers to the problems suffered during the Belgian GP weekend.

"It's not nice when you're driving at over 300km/h and you have a tyre giving up," said Nasr.

"We have to look at the side of safety and to think what they can do about it.

"This is something Pirelli and F1 will know better than I do. It has to come from them.

"It is worrying when you have so many cases. We need facts to know what is really happening."

Nasr added he was curious to know if the kerbs at Spa had played a part, as the Sauber drivers use the kerbs less than many of their rivals.

"I don't know if it was something on the track or a kerb that was cutting the tyre," he said.

"We don't run many kerbs because our car isn't good over the kerbs.

"We didn't have problems with tyre cuts but other teams did."