Barcelona F1 test: Felipe Nasr fastest while McLaren struggles

GP2 graduate Nasr, who topped the third day of the opening test at Jerez, went fastest just after the morning's mid-point and bettered his time by two-tenths with a 1m27.307s run on medium-compound Pirellis half an hour later.

That improvement kept him top by just 0.056s from Daniel Ricciardo, who made a late flourish in the Red Bull to rise up the leaderboard having only completed a number of installation laps until that point.

The RB11 only managed 18 laps in total but its late progress meant its morning was the opposite of McLaren's, which had made a much more promising start to the test before its latest technical issue.

Jenson Button was second quickest for much of the morning in the Honda-powered MP4-30 and, having had his fastest lap taken away, his next-best effort was less than a second slower than Nasr's benchmark by the end.

But an issue with the engine's MGU-K seal meant Button returned to the pits shortly after the morning's halfway mark with 21 laps completed and did not emerge again.

In his absence Pastor Maldonado jumped to third, 0.2s slower than Nasr, despite causing two red flags when his Lotus E23 stopped on track at almost the same point, the second time only moments after re-emerging from the pits.

Max Verstappen backed up Renault's pace (with Red Bull) with the fourth-fastest time in the Toro Rosso, and the 17-year-old was just over a tenth clear of morning pace-setter Kimi Raikkonen, who lost his best time due to corner cutting at the chicane.

Pascal Wehrlein appeared in two different cars. The Mercedes reserve was driver seventh quickest in the 2014-specification Force India before setting the eighth-best time when he had to sub in for world champion Lewis Hamilton.

The Briton completed just 11 laps before abandoning his running through illness.

He propped up the times, one second slower than the Williams of Susie Wolff, who amassed a morning-best mammoth 77 laps.

Morning session times: