BARCELONA, Spain - Lewis Hamilton ensured Mercedes finished quickest at the first F1 preseason test, where Fernando Alonso and Alpine's day went up in smoke in the morning.
Hamilton, who is looking to win a record eighth F1 championship this season, set two quick laps in the final 20 minutes.
On the C4 tyre he set a 1:19.141 before switching to the C5, the softest and quickest tyre in Pirelli's test range, and went 0.003s faster to finish the test with a best time of 1:19.138.
McLaren and Ferrari had grabbed the headlines on the opening two days but Mercedes ensured it left Barcelona with both its drivers top of the order. George Russell's 1:19.233, set in the morning, was good enough for second on the board.
Red Bull occupied the next two spots, with Sergio Perez on a 1:19.556 and Max Verstappen on a 1:19.756.
Lap times tend to be misleading during preseason, especially during the opening few days, with multiple unknown variables such as fuel loads, engine modes and general car set-up. Times set at different points in the day, when weather and temperature can change drastically, is another variable in play.
Despite a quieter third day in terms of outright times, the feeling in the F1 paddock is that McLaren and Ferrari have both had a hugely encouraging start to preseason and both were very productive in terms of mileage on Friday.
McLaren completed 138 laps between Lando Norris and Daniel Ricciardo either side of the lunch break, while Ferrari managed 136 between Carlos Sainz and Charles Leclerc.
At the other end of the mileage scale was Haas, running a plain white car after deciding to remove the colours and logo of title sponsor Uralkali in the wake of Russia's military invasion of Ukraine.
Nikita Mazepin, who's future with the team remains in doubt as Haas weighs up what to do about its Uralkali partnership beyond this week, completed only nine laps across the day as Haas was limited by an oil leak in the car.
F1 has three more days of testing at Bahrain's Sakhir International Circuit between March 8-10, which is where attention is more likely to turn towards outright one-lap and race pace.
That venue will then host the opening race of the season, the Bahrain Grand Prix, on March 20.
After two days and 16 hours with just two red flag stoppages, there were five on Friday morning in a massively disrupted session.
The first one, caused by Fernando Alonso, was the most dramatic. Alonso was told to stop his car in the final sector after losing pressure when his car then caught fire. It was surrounded by plumes of smoke when marshals arrived with fire extinguishers.
Alpine said it had been a hydraulics problem and that "a minor sealing issue led to a fire in the back of the car".
It meant Alonso and Alpine finished the day with just 12 laps on the board and effectively lost one-third of the time available to the teams this week.
AlphaTauri also had a shortened day when Pierre Gasly crashed his carat Turn 5, prompting the second red flag of the day. Pictures of Gasly's car showed it had damaged front suspension on both sides as well as damage to the front wing following contact with the wall.
The incident ended Gasly and AlphaTauri's day early.
Alfa Romeo rookie Guanyu Zhou prompted a pair of red flags in the space of 30 minutes, once when he beached his car in the gravel and another when it crawled to a halt after a loss of power on the start-finish straight.
Aston Martin caused a further red flag when an oil leak resulted in a small fire at the back of Sebastian Vettel's car, forcing him to stop on track.
Alfa Romeo and Aston Martin also were unable to get their cars back out on track, meaning only five teams -- Mercedes, Red Bull, Ferrari, McLaren and Williams -- took part in the afternoon session.
1. Lewis Hamilton - Mercedes - 1:19.138 - 94 laps
2. George Russell - Mercedes - 1:19.233 - 66 laps
3. Sergio Perez - Red Bull - 1:19.556 - 74 laps
4. Max Verstappen - Red Bull - 1:19.756 - 59 laps
5. Sebastian Vettel - Aston Martin - 1:19.824 - 48 laps
6. Charles Leclerc - Ferrari - 1:19.831 - 44 laps
7. Carlos Sainz - Ferrari - 1:20.072 - 92 laps
8. Alex Albon - Williams - 1:20.318 - 94 laps
9. Nicholas Latifi - Williams - 1:20.699 - 13 laps
10. Daniel Ricciardo - McLaren - 1:20.790 - 86 laps
11. Lando Norris - McLaren - 1:20.827 - 52 laps
12. Fernando Alonso - Alpine - 1:21.242 - 12 laps
13. Guanyu Zhou - Alfa Romeo - 1:21.939 - 41 laps
14. Pierre Gasly - AlphaTauri - 1:22.469 - 40 laps
15. Nikita Mazepin - Haas - 1:26.229 - 9 laps
16. Valtteri Bottas - Alfa Romeo - 1:30.433 - 10 laps