Sebastian Vettel finished the opening day of the first pre-season test quickest for Ferrari, although the German failed to improve on his 1m24.939 from the morning session, but it was enough to ensure he remained atop the timing screens as the checkered flag fell in Barcelona.
Reigning world champion Lewis Hamilton finished almost half a second down on Vettel's best effort, though the Briton clocked up an impressive 156 laps – the same distance as two grands prix and 28km more than Nico Rosberg achieved at the first test of the 2015 season.
It was a trouble-free day for most. A single red flag came out for Romain Grosjean who lost his front-wing due to structural failure. Haas hope to have a fix in place for day two of the test.
Red Bull's Daniel Ricciardo finished third fastest, a second down on Vettel. Third was closely contested between Ricciardo, Williams' Valtteri Bottas and Force India's Alfonso Celis, with the trio split by just over two-tenths.
Jenson Button will be pleased with McLarens efforts. The Briton was sixth fastest with a 1m26.735 and racked up 85 laps in the process, compared to just six for Fernando Alonso at the opening test last year.
Toro Rosso's Carlos Sainz lapped the Barcelona circuit 55 times, but couldn't go out for his final run due to a data abnormality. A time of 1m27.180 put him seventh ahead of Sauber's Marcus Ericsson and Manor's Pascal Wehrlein.
Jolyon Palmer rounded off the 11 runners with a 1m29.356, almost 4.5 seconds adrift of Vettel's lead time.
Pre-season testing – Test 1 – Day 1 Final Times: