Sebastian Vettel and Red Bull dominated the second practice session at the Belgian Grand Prix, before a tyre puncture brought a halt to his proceedings.
Pirelli said the cause of the problem was being investigated, with Vettel topping the timesheets with a lap time of 1:49.331.
Red Bull teammate Mark Webber was second ahead of Lotus' Romain Grosjean.
"The only thing that really matters is that we understand why it (the tyre puncture) happened," Vettel told Formula One's official website. "So far we have not understood, so we will have a long evening evaluating the data."
Even though the practice session was dry, Vettel is preparing himself for all sorts of weather conditions.
"Today (Friday) we've had pleasant conditions, but we know that Spa has very different sides -- and very likely we will see these sides tomorrow (Saturday) and on Sunday," Vettel said.
"So there is not really much that you can do in defining your set-up today when you know that it will not have any value when it is ten degrees colder and raining. The thing that you can do is to try to understand how the tyres react -- the softer as well as the harder compounds."
Vettel said he was reasonably satisfied with his team's performance so far this season, but believes they can do better.
"I would say that we are doing very well, but not perfect," he added. "Especially lately we have had made zero points in Silverstone, so there is still some improvement to do. For us it is very important that we still are hungry for wins and enjoy racing itself very much.
"We generally do not look at the scorecard, as this would rather distract us and for now it is just far too early to do that. I am sure that we will have more need for this maybe later in the season."
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