San Francisco Frontiers - Russell tops the times for Mercedes in opening practice

Making the most of reliability problems for world champion Max Verstappen and the Red Bull team, the 24-year-old Briton clocked a best lap in one minute and 29.938 seconds to outpace championship leader Charles Leclerc of Ferrari by 0.106.

His performance suggested that, following four poor early-season races, the Silver Arrows' package of aerodynamic upgrades was working.

Sergio Perez of Red Bull was third, a further tenth adrift, narrowly ahead of seven-time champion Lewis Hamilton in the second McLaren.

Hamilton was given a late exemption to take part in the event with his nose ring following a clampdown on 'driver bling', having removed all of his other jewellery shortly before the opening session.

Fernando Alonso was fifth for Alpine ahead of McLaren's Lando Norris and Pierre Gasly of Alpha Tauri in a session interrupted by two red flags on a warm, dry day at the new Miami International Autodrome.

Leclerc had topped the times ahead of Russell in the opening morning session, but was unable to repeat the feat in the afternoon when Ferrari team-mate Carlos Sainz crashed again.

In front of an enthusiastic sellout crowd in Miami Gardens, the session began with Esteban Ocon setting the pace on mediums, the track having cooled to 44 degrees following a frantic morning session topped by Leclerc.

It did not last long for the Alpine driver as he was soon outpaced by Sainz before Leclerc took command and the Ferrari men traded fastest laps.

Verstappen missed the early action as Red Bull decided to change his gearbox after he had grazed a wall during the first session.

Valtteri Bottas, of Alfa Romeo, was also inactive after his morning crash.

Perez, in the second Red Bull, managed to split the Ferraris after 23 minutes before Sainz triggered the second red flag of the day when he spun backwards into the barriers at Turn 14.

He was unhurt, but after setbacks in Melbourne and Imola, it was another blow to his confidence.

After a 12-minute delay, during which Perez's crew helped on the world champion's car, Verstappen emerged to join the fray only to be called back to the pits.

"I can't steer," said Verstappen, who was almost involved in a collision with Lance Stroll's Aston Martin as he struggled.

He returned to the track, but the rear brakes on his car overheated and caught fire – as chief rival Leclerc went fastest on softs in 1:30.044 only to be surpassed by Russell in 1:29.938, a lap that confirmed the Silver Arrows revival.

With 20 minutes remaining, Russell led Leclerc and Perez with Hamilton fourth and Verstappen frustrated without a timed lap. His problem was diagnosed as a hydraulics issue.

Another red flag followed, with 12 to go, when Nicholas Latifi pulled up and stopped in his Williams, before a final flurry of action.

V.Perez--SFF