Max Verstappen set the pace during opening practice in Singapore, as in-form Charles Leclerc encountered mechanical woes, while Valtteri Bottas crashed heavily.
In overcast and hazy conditions, with the 90-minute session held at daytime, Verstappen moved to the front with a time of 1:40.259, set on the Soft tyres.
Verstappen, who has never won at the Marina Bay Street Circuit, finished 0.167s clear of four-time Singapore victor Sebastian Vettel.
Points leader Lewis Hamilton was third for Mercedes, 0.666s in arrears, as he set his best effort on the Hard tyre, indicating that there is substantially more pace to come from the W10.
Nearest title rival and team-mate Bottas brought out the only red flag in the session when he crashed through Turn 19.
Bottas, who still classified fourth in the session, lost control on entry to the right-hander and suffered a hefty impact, sustaining damage to the front-left of the car.
Alexander Albon, who admitted on Thursday that he would take time to get up to speed at the venue, was fifth, 1.2s behind his Red Bull team-mate.
Leclerc, who has won the last two races from pole position, finished down in 19th after he suffered a gearbox problem.
The youngster slowed as he rounded Turn 20 and was able to crawl back to the pit lane in order for his mechanics to retrieve his stricken SF90.
Outgoing Renault driver Nico Hulkenberg was sixth, 1.5s behind Verstappen, with McLaren pair Carlos Sainz Jr. and Lando Norris seventh and eighth respectively.
Toro Rosso duo Daniil Kvyat and Pierre Gasly rounded out the top 10, in front of Daniel Ricciardo, Romain Grosjean, and the Alfa Romeo duo of Antonio Giovinazzi and Kimi Raikkonen.
Lance Stroll and Kevin Magnussen were the slowest of the Soft tyre runners in 15th and 16th, while Robert Kubica was 17th on Mediums, three spots ahead of Williams team-mate George Russell.
Sergio Perez, who cancelled his Thursday media sessions due to illness, was 18th, having set his best time on the Hard tyres.
Friday’s second 90-minute practice session is scheduled for 20:30 local time
