The Mercedes driver, who had complained about his car’s rough handling early on, fitted a new set of soft redwall tires and ran the fastest in 0.084 seconds.
This relegated Verstappen, the Red Bull driver who dominated much of the hour, to second while Leclerc overcame initial braking difficulties to complete the top three.
Verstappen was seemingly operating in a league of his own from his early laps in opening practice as the Dutchman finished the first 25-minute stint with a 1.1-second cushion over Fernando Alonso.
The Alfa Romeo opened the baton to an air of cheers from the stands, but it took Carlos Sainz posting a 1m50.961s for anything like a representative time to be established.
But keeping the type in 2022, Verstappen ruined it all with his first lap as he covered the 3.15 miles in 1m47.329s on the medium yellow-walled Pirellis to lead team-mate Sergio Perez.
Alonso then dropped off the Red Bull before spending the rest of the session trying to split the RB18s at the top before Verstappen continued to drop each time to set the pace.
After 10 minutes, Verstappen reduced his benchmark to 1m45.466s to find some 1.825s over Alonso, then lowered it further into the 1m44s, running fastest in all three sectors to set the pace at 1m44.236s to find 1.1s on Alonso. while Perez ran third in a 1m45.349s.
Having completed only one set-up lap before Leclerc was forced to pit for 25 minutes to remedy brake issues, Sainz led the Ferrari charge to fourth thanks to his 1m45.628s set on the slower hard compound. The Spaniard requested major setup adjustments after his first race.
Max Verstappen, Red Bull Racing RB18
Photo by: Carl Bingham / Motorsport Images
Although there were occasional spikes of oversteer and shake, the only notable incident in the first half of the hour came when George Russell slammed into the barriers at Turn 11.
He locked the inside wheel while slowing to the tight right and continued straight, but quickly reversed the undamaged Mercedes and took it for a precautionary visit to the garage.
However, Lance Stroll would induce a full red flag with 20 minutes to go after the then-fourth Aston Martin driver slid wide at Turn 5 and hit the outside wall.
On the right-hander where Sainz had backed off with a huge slide, Stroll buckled the left rear corner of his car and suffered a puncture to stop and force the session to a halt.
Although the first and second sectors were under yellow flags, Verstappen creaked just in time to post a purple 1m43.117s on soft tires to unseat Perez by seven tenths.
FP1 resumed four minutes later but only five cars came out including Sainz’s F1-75 which ran on soft tires up to 1m44.138s to sit third but was a full 1s behind Verstappen – in part until a massive rear end drag in the last turn that forced it wide wide.
Charles Leclerc Ferrari
Photo by: Carl Bingham / Motorsport Images
Leclerc came very close to rival Red Bull on his fast first lap in soft, although he too was struggling with a nervous car. The Monegasque posted a 1m43.435s to run the second fastest, dropping three tenths to Verstappen but having set the fastest time of all in the middle sector.
But with five minutes to go, as Verstappen raced on mediums and locked in to take the turn 16 escape route, Hamilton surged to the top of the timing screens – helped by a bit of track evolution – eight hundredths thanks to its load of 1m43.033s of effort in the W13.
Verstappen would therefore take second place, with the defending champion having a 116-point lead, while Leclerc – who needs to finish ninth or higher to challenge for the title at the next race in Japan – was third.
Perez finished fourth for Red Bull, which along with Aston Martin is believed to have exceeded the 2021 budget cap, while Russell was fifth ahead of Sainz.
Alpine’s effort would be led by Esteban Ocon in seventh as Stroll slipped to eighth ahead of Pierre Gasly and Alonso. Sebastian Vettel took 11th ahead of Daniel Ricciardo, who did not receive the wealth of McLaren upgrades for this weekend.
Behind Valtteri Bottas, Kevin Magnussen and Yuki Tsunoda was Alex Albon in 16th, the Thai Briton returning for the Marina Bay weekend after missing the Italian GP with appendicitis before suffering respiratory failure.
Results F1 Singapore GP – FP1