The Fort Worth Press - Leclerc shows practice pace as Antonelli prowls in Mexico

The Monegasque driver clocked a best lap time in one minute and 18.128 seconds to outpace the young Italian by 0.659 seconds in a session, with 10 rookie reserve drivers in action, that was punctuated by a brief Virtual Safety Car intervention.

Antonelli, who had been absent from the circuit on Thursday to recover from a virus, can become the sport's youngest world champion on Sunday, and Italy's first since 1953, if he finishes in the top nine.

He can also take the title if his two remaining rivals -- Mercedes team-mate George Russell and Ferrari's seven-time champion Lewis Hamilton -- fail to win.

Russell sat out FP1 and watched as his replacement, reserve Frederik Vesti, finished third-fastest in the second Mercedes ahead of Hamilton. Another rookie Ayumi Iwasa was fifth for Red Bull in the car normally occupied by four-time champion Max Verstappen.

Pierre Gasly was sixth for Alpine ahead of Aston Martin's two-time champion Fernando Alonso, Oscar Piastri of McLaren, Oliver Bearman of Haas and Racing Bulls' Arvid Lindblad.

Isack Hadjar, in the second Red Bull, was 11th after struggling with power unit problems.

Hamilton was first out at the start of the session, his Ferrari carrying aero rakes to provide data for the set up. He was followed by three of the 10 rookies, including several considered future stars.

The Briton earlier confirmed that he intended to continue racing "for the foreseeable future" so long as he remains competitive in a bid to take part in the planned African Grand Prix in Rwanda.

"You've never had anyone like me here in the 70 years," he told reporters, as he outlined his ambitions, stressing that his fitness and reactions remained undimmed.

"I feel that I'm built differently," he said. "I'm still all in, and I will be for the foreseeable future."

Ferrari were the only team not to run a rookie in FP1 on a high-altitude circuit where engines struggle with the thin air, which, at 2.285 metres, has only 78 per cent of the density at sea level.

Perez, preparing for his 300th F1 race after signing a multi-year contract extension, clocked an early fastest lap for Cadillac before the usual suspects took control with Antonelli, Leclerc and Hamilton leading the way.

The young Italian, like Perez and his team-mate Valtteri Bottas, had been hit by a virus, but he looked as fast and determined as ever.

Leclerc continued the form he enjoyed in Texas ahead of last weekend’s United States Grand Prix when he was fastest in both Friday sessions.

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W.Lane--TFWP