World champion Lewis Hamilton hammered out an early-season warning to his Formula 1 rivals by setting the fastest time on the opening day of pre-season testing in Barcelona.
Hamilton, who will attempt to equal Michael Schumacher's all-time record of seven world titles this year, clocked a best time of one minute 16.976 seconds off a total of 94 laps - the only driver at a chilly Montmelo to duck under 1:17 minutes.
Worryingly for the rest of the field, Mercedes teammate Valtteri Bottas was second fastest in 1:17.313 minutes.
"It's been a good day and a really good start for all of us, considering we had a long break," said Hamilton. "So to come back and clock in over 170 laps just shows how hard everyone has been working over the winter."
Sergio Perez, in a Racing Point, was fourth best at 0.399 seconds off the pace while Red Bull's Max Verstappen was fourth at 0.540 after putting in 168 laps, the most by any driver.
"It's been a good day," said Verstappen. "It's always important to do as many laps as possible and today was a really good example of how you should do it, so I'm very happy."
The season-opening Australian Grand Prix takes place in Melbourne on March 15.