Sebastian Vettel reckons Sir Lewis Hamilton and Fernando Alonso are the most challenging opponents he has come up against in his career.
Alonso won two world championships in 2005 and 2006 with Renault, before an unsuccessful move to McLaren led him back to Enstone.
The Spaniard was twice beaten by Vettel to the championship in his Ferrari career between 2010 and 2013, in exhilarating title battled that went down to the wire.
Further moves back to McLaren and Renault, under their new Alpine guise, have varied in their benevolence to the 41-year-old, who still awaits his first win since the last of his 32 in 2013.
READ: Sebastian Vettel warns Fernando Alonso as he admits Aston Martin ‘fell into trap’
Hamilton entered Formula 1 with McLaren in the same season as Alonso first joined the British side in 2007, winning four races and finishing level on points with his team-mate.
They lost out to Kimi Raikkonen by a single point after a tumultuous season that saw the Spaniard fall out with Ron Dennis, ultimately leading to his exit.
After his first championship in 2008, Hamilton went four years without one, prompting a daring, but genius, move to Mercedes, with whom he has won a further six titles.
Two of those arrived while he was up against Vettel in 2017 and 2018, with the pair winning 30 races between them.
The Briton claimed both titles with two rounds to go of the season in Mexico, after strong starts to the season by Ferrari deteriorated.
Vettel was not able to replicate the success with Ferrari that he had during his time at Red Bull, winning four titles on the trot between 2010 and 2013.
Having spent the last couple of seasons racing further back with Aston Martin, the 35-year-old has decided to call it a day, but he has some memories of racing with the very best this sport has had to offer.
“Lewis, especially when I was at Ferrari, Lewis has always been right up there,” said Vettel when asked by Aston Martin’s media team who his toughest rivals were.
“Before that, it was probably Fernando when he was at Ferrari.”
Alonso will replace Vettel at Aston Martin next season, and as a two-time champion and still one of the quickest on the grid in his forties, he should be just fine without anyone giving him any guidance.
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“Fernando doesn’t need any advice. I’m not sure he’s taking any advice, but he doesn’t need it anyway. He’s been around for so long and seen so much – he’ll be fine,” added Vettel.
Alpine have replaced Alonso with AlphaTauri’s Pierre Gasly after Oscar Piastri’s signature with McLaren, while the Red Bull junior team have brought in former Formula E champion, Nyck de Vries.
That leaves Haas and Williams as the only two teams yet to finalise their plans for 2023.