Lewis Hamilton struck an early warning on the opening day of Formula One testing in Barcelona by posting the fastest lap.
Hamilton is bidding to equal Michael Schumacher's record with a seventh world championship, and he finished a third of a second clear of Valtteri Bottas in the sister Mercedes at the Circuit de Catalunya.
"It's been a good day and a really good start for all of us, considering we had a long break," said Hamilton. "It just shows how hard everyone has been working over the winter."
Red Bull and Max Verstappen are hoping to lead the challenge to Hamilton. The 22-year-old Dutchman ended the day in fourth.
Sebastian Vettel withdrew from the opening day after falling unwell.
The four-time world champion was due to kick off Ferrari's pre-season campaign, but Ferrari confirmed Vettel would not be in action, with team-mate Charles Leclerc assuming driving duties for the Italian team.
Vettel, 32, posed for a group picture with all the drivers before he left the track.
The first test concludes tomorrow, with three further days of running in Barcelona next week. Hamilton will open his title defence in Melbourne on March 15.