Daniel Ricciardo ended the first day of pre-season testing at the Circuit de Barcelona-Catalunya on top of the timesheets.
The Red Bull driver was fastest in the morning session with a time of 1:20.179s after completing 60 laps in the new RB14. He added another 45 after lunch, making him the hardest working driver of the day.
Overcast and unusually cold conditions made it hard for anyone to improve on the earlier times during the afternoon. Rain picked up during the final hour, allowing any teams so inclined to briefly try out intermediate tyres.
The inclement weather meant Valtteri Bottas remained second fastest overall for the day. That was despite handing over the Mercedes W09 to his team mate Lewis Hamilton at midday.
Hamilton's subsequent best time of 1:22.327s after 25 laps was almost a second off Bottas' morning effort, putting the Briton seventh fastest.
Kimi Raikkonen was third-fastest on 1:20.506s in the new Ferrari SF71H, and Nico Hulkenberg was fourth with 1:20.547s. Raikkonen continued in the car after lunch but only added 20 laps to his morning total of 60.
Hulkenberg had completed the most laps of anyone in the morning - 73 - before handing over the R.S.18 to his team mate. Carlos Sainz completed a further 26 laps and was sixth fastest for the day on 1:22.168s.
One of the few morning drivers to improve his time in the afternoon was Fernando Alonso. After brushing himself down after his early foray into the gravel due to a wheel nut failure, he put in 41 laps in the afternoon. He duly improved his time to 1:21.339s, good enough for fifth fastest on the day's timesheets.
A full day's work saw Toro Rosso's Brendon Hartley notch up 93 laps, a tally bettered only by Ricciardo. The Kiwi set the seventh fastest time lap of 1:22.371s in the process.
Lance Stroll's morning time of 1:22.452s remaibned good enough for eighth overall. His Williams team mate Sergey Sirotkin then took the afternoon to accustom himself to the FW41. Despite completing 28 laps, he wasn't able to set a representative time before conditions deteriorated.
Romain Grosjean completed 55 laps in the Haas VF-18 but his best time was only 1:22.578s. Marcus Ericsson (Sauber) and Nikita Mazepin (Force India) were even further off the pace. The Russian test driver only completed 22 laps, the least of any of the 13 drivers taking part. He did not take any further part after lunch.
Pre-season testing Day 1 - final times