Daniel Ricciardo set the morning pace on the second day of Formula One testing in Barcelona.
The Red Bull driver's best time of 1:24.574 was around half a second quicker than the benchmark set by Lotus driver Pastor Maldonado on the opening day of testing.
Like Maldonado, Ricciardo set his time using the soft Pirelli tyres.
The Australian finished just 0.010 seconds ahead of Kimi Raikkonen in the Ferrari, the Italian squad enjoying another strong start to the day.
Force India's Sergio Perez was third in the 2014 car, less than two tenths of a second off the pace.
Nico Rosberg was in charge of testing duties for Mercedes despite being in doubt due to the problems with his neck, the German having a productive morning on his way to the fourth fastest time.
Despite the fear that its work would be interrupted again following yesterday's problems, McLaren had a promising first half of the session with Fernando Alonso.
The Spaniard covered 28 laps and wound up fifth ahead of Felipe Massa in the Williams and the Sauber of Marcus Ericsson.
GP2 champion Jolyon Palmer made his debut at the wheel of the Lotus E23, the Briton setting the eight quickest time after 31 laps.
Carlos Sainz took over from Toro Rosso teammate Max Verstappen and was slowest.
There was only one red flag in the morning, when Ricciardo had to be pushed back into his garage after stopping in the pitlane.
|1.||Daniel Ricciardo||Red Bull-Renault||1:24.574||64|
|3.||Sergio Perez||Force India-Mercedes||1:24.702||+0.128||44|
|9.||Carlos Sainz||Toro Rosso-Renault||1:28.945||+4.371||42|