A late lap from Max Verstappen saw the championship leader narrowly better Charles Leclerc in the only practice session for the F1 Azerbaijan Grand Prix.

The Red Bull driver was just 0.037s faster than his Ferrari rival in a session he had topped for much of it.

A red flag midway through the 60-minute hit-out cost all teams critical track running when Pierre Gasly and Kevin Magnussen struck trouble.

Results: Formula 1 Azerbaijan Grand Prix, Practice 1

It was a predictably busy start as the session began.

Most opted for the hard or medium rubber though Scuderia AlphaTauri fitted a set of softs for Nyck de Vries and Yuki Tsunoda.

That selection was an admission of low expectations, as the fastest compound tyre is mandatory at points during the latter stages of qualifying.

Carlos Sainz had a brush with the barrier at Turn 5 inside the opening 10 minutes.

The Ferrari driver grazed the barrier on the apex of the left-hander, though managed to escape without damage.

At Mercedes, both George Russell and Lewis Hamilton reported brake issues.

There were early dramas for Tsunoda too, who picked up a right-rear puncture.

He limped the Scuderia AlphaTauri back to the pits, the tyre coming off the rim while recovering the car to the pits.

It resulted from a spin at Turn 3, sliding wide and clipping the right rear on the tyre wall.

There was significant damage to the car, with damage to the floor and other areas caused by the flapping tyre as he dragged it home.

As he was doing that, Verstappen sat atop the timesheets with a 1:43.834s, heading team-mate Sergio Perez by just under 0.3s.

Pierre Gasly struck trouble in his Alpine with fire in the rear of his car.

A loss of hydraulic pressure manifested itself out of Turn 1 after 15 minutes, the Frenchman carrying on to bring the car home.

With little practice, there was a strong incentive to get the car back to the pit lane.

The red flag was shown as he reached the Castle section, Gasly stopping the car and climbing free.

Kevin Magnussen had also stopped on the run-off at Turn 1 and could not get the car back on track.

According to team boss Guenther Steiner, the Dane lost fuel pressure and ultimately climbed out of the car and walked back to the Haas garage.

Running resumed with 32 minutes remaining.

Having lost time earlier on, Hamilton was immediately out on track.

The Mercedes driver had not set a time before the stoppage after being beset by brake issues.

At Alpine, the day only got worse for Esteban Ocon, who was stuck in the pits as the team worked on his car.

The Frenchman was out of the car, which sat on stands.

With 20 minutes remaining, Verstappen remained fastest from Perez, with Carlos Sainz third best,

The second Ferrari of Charles Leclerc was next best, while the Aston Martins were again showing pace.

The surprise was Scuderia AlphaTauri, Nyck de Vries sitting sixth fastest with strong straight-line speed.

His best lap to that point, a 1:44.866s, was set on the medium compound tyres suggesting the Dutchman may figure more prominently than the squad expected given its early tyre strategy.

Stroll soon improved to second best, though still 0.219s down on Verstappen.

Across the garage, Fernando Alonso was told to head to the pits after complaining of DRS issues.

Oscar Piastri ventured out on a set of soft compound tyres with 15 minutes remaining after running through a testing programme earlier in the session.

He sat 19th at the time though his best was not representative given his initial focus on gaining data on McLaren’s new upgrade package.

That resulted in the seventh fastest lap, a 1:44.558s, to sit 0.930s down on Verstappen’s best.

The Dutchman had been sent out on soft tyres inside the final 10 minutes as qualifying simulations began.

Verstappen improved to 1:44.042s, a time bettered by Perez, who logged a 1:42.651s.

Alex Albon had briefly held the top spot after his single lap run, managing a 1:43.628s for Williams.

As it had been at the start of the session, it was in the final minutes as the circuit became a hive of activity.

Leclerc put his Ferrari second fastest, just 0.093s away from Perez, as Sainz slotted into fourth.

Such was the improvement throughout the field; Piastri found himself quickly bundled to 12th, 1.8s away from the pace laid down by Red Bull.

That benchmark improved with two minutes remaining, with Perez logging a 1:42.600.

It lastest barely a minute before Leclerc went a quarter of a second faster to put his Ferrari atop the timesheets.

As the chequered flag waved, Verstappen went fastest with a 1:42.315s, just 0.037s better than Leclerc managed.

The Monegasque ended the session second from Perez, Sainz, Norris, de Vries, Stroll, Alonso, Albon, and Zhou Guanyu.