Although Fernando Alonso will be 39 when he returns to Formula One next season with Renault, he feels his reflexes and racing craft will not weaken with age.
His widely-anticipated F1 return became official yesterday, when the French manufacturer announced he will replace Australian driver Daniel Ricciardo next year.
Alonso won his world titles with Renault way back in 2005 and 2006 but still looked sharp driving an uncompetitive car during his last season with McLaren in 2018 before walking away.
"The stopwatch is the only thing that matters, not the age," he said. "I never had a classification on the race based on the passport, my date of birth. It's always on stopwatch. Hopefully we're still fast."
That remains to be seen considering Renault struggled last season, finishing fifth in the constructors' championship, one place behind McLaren, the team it supplies engines to. But Alonso certainly feels in good enough shape.
"I had to start very specific fitness preparations, I started in February, so now I'm 100 per cent," he said. "We did a couple of fitness tests 15 days ago and I had the best results in my career, so I'm extremely motivated, happy and stronger than ever."
However, because of rule changes teams will use the same cars for 2021 and Alonso may not have a genuinely competitive car until 2022, when he will turn 41 in late July.
"I will try to do my best, and try and help the team be a world champion team. If that's with me driving, fantastic but if that's with a future younger driver, I will feel proud anyway," he said.
"I think the 2022 rules will hopefully bring some fairness to the sport and some close action with teams more level and less scope to invent something that has a large performance advantage."
Alonso, who will race alongside French driver Esteban Ocon next year, had quit F1 to focus on winning motorsport's triple crown. Having already won the Monaco Grand Prix, he then won the 24 Hours of Le Mans endurance race, but not the Indianapolis 500.
Alonso won 32 F1 races and has 97 top-three finishes.