Red Bull's Daniel Ricciardo edged a tightly contested second day of Formula One pre-season testing in Barcelona.

At the end of Friday's session, less than a tenth of a second covered the Australian, Ferrari's Kimi Raikkonen and Williams' Felipe Massa.

Raikkonen was only one-hundredth of a second shy of Ricciardo's best mark of one minute and 24.574 seconds, with Massa a further 0.098secs back.

Ricciardo's 143 laps will be useful for Red Bull's pre-season progress.

Mercedes were not among the frontrunners for pace, but Nico Rosberg and Lewis Hamilton compiled an impressive 145 laps between them.

Rosberg - who announced he was set to become a father earlier in the day - had been slated to take part in all of Friday's action, but a trapped nerve in his neck kept him out of the afternoon session, allowing Hamilton to fill in after missing Thursday's sessions through illness.

Ferrari's newfound pace has been a major talking point of testing so far and, though the Italian team have been keen to play its significance down, Rosberg's alert is up.

"It's clear that the others have really stepped up their game," the German said.

"The lap times are surprising to us and in relation it seems that Ferrari have made the biggest step."

McLaren enjoyed their first day of real success so far, Fernando Alonso completing over 50 laps despite fears over an engine issue which had curtailed Jenson Button's progress a day earlier.

GP2 champion Jolyon Palmer was eighth fastest on his first test for Lotus, as Marcus Ericsson in the Sauber and Carlos Sainz Jr in the Toro Rosso completed the top 10.

Sainz, the son of former rally world champion Carlos Sainz, brought out the red flags when he ended up in the gravel on turn nine.

Testing resumes on Saturday at the Circuit de Catalunya and concludes on Sunday.