McLaren duo frustrated by interruptions

"It's very difficult doing any kind of set-up changes when there's so many red flags. It's surprising how many red flags we've had today," Button commented.

"One touch of a kerb in the wrong way can send you into a wall, so it's not perfect. Hopefully tomorrow will be a nice clean day."

"That's racing," observed Hamilton. "People are testing the limits of the cars and you would be blaming them if they didn't try."

The second session's two red flags were a particular hindrance, and especially for Hamilton, who collected a puncture on his first lap on track right after Jerome D'Ambrosio hit the wall at Turn 4.

"I think it must have been debris, because I'd only just gone out," he said.

In both sessions, the pair were around a second off the fastest pace while not really focusing on low-fuel running. Button (fifth place) edged Hamilton (sixth) in first practice, with roles reversed in the second session as Hamilton finished fourth, one place ahead of his colleague.

Despite the difficulties of the impromptu breaks, McLaren logged a total of 90 laps on Friday, and both Button and Hamilton are feeling enthusiastic about the long-run data they have accumulated.

"We've done some high-fuel work with the soft tyre and I think that was key today, to really get some laps on the super-soft," said Button. "I think it was useful information, and hopefully [tomorrow] we can improve the car on low-fuel."

"It was a very good day for me, we got through a lot of test components and we're just trying to find the exact balance I want," added Hamilton. "We're going to go and sit down and analyse some things. Long-run pace is not so bad so I think the speed is there."