Red Bull's Formula One leader Max Verstappen has kept Ferrari's home hero Charles Leclerc off the top of the timesheets, while Carlos Sainz, quickest in the first session, crashed in second practice for the Monaco Grand Prix.

Double world champion Verstappen's best effort of one minute 12.462 seconds was just 0.065 quicker than Leclerc's fastest around the treacherous city streets on Friday and came after the Dutch driver had earlier struggled with the car's set-up.

Australia's Oscar Piastri (1:13.673) had a struggle on his debut in the world's most famous F1 race, finishing 18th of 20 in second practice, while his McLaren teammate Lando Norris impressed in fifth (1:12.906).

Leclerc will be going for his third successive Monaco pole position on Saturday and hoping for a first home podium on Sunday.

Ferrari's Sainz, who clocked 1:13.372 in the morning, was third fastest in the second session but crashed after clipping the barriers at the exit to the Swimming Pool chicane.

The impact broke the car's front right suspension, with red flags waved to halt proceedings.

"Yeah, I crashed. Sorry," the Spaniard told the team, who had company president John Elkann keeping a close eye on proceedings, over the radio.

Compatriot Fernando Alonso was fourth fastest for Aston Martin ahead of a race he has won twice before and believes he can win again.

Alonso, four times third-placed on the podium from five races so far this season, had been second in the day's opening session that was twice red-flagged after drivers hit the barriers.

Seven-times world champion Lewis Hamilton steered his new-look Mercedes, with significant changes to sidepods and suspension, to the third best time in practice one and sixth in the second.

Last year's winner Sergio Perez, now 14 points behind Verstappen in the championship, was fourth and seventh respectively for Red Bull.

Perez had warned before the start of the track action that Monaco was not Red Bull's strongest circuit, despite the champions going unbeaten so far in 2023 with four one-two finishes and winning the last two editions of the race.

The Mexican identified the Ferrari drivers and Alonso as the biggest threats, a prediction that looked on the money for Friday at least.

The first session ended three minutes early when the red flags came out after Alex Albon crashed his Williams at the exit to the Sainte Devote first corner, wrecking the left side of his car.

Albon returned for the second session with a replaced gearbox and changes to the rear and front wings, suspension and floor.

Practice was also suspended when Nico Hulkenberg clipped the barrier and spun his Haas at the Nouvelle Chicane after the tunnel.

McLaren's Lando Norris was seventh and then fifth fastest, much quicker than his rookie teammate Piastri, who was 17th and 18th.