Lewis Hamilton may go on to win 10 world titles, but his status as the greatest could be undermined by a lack of true rivals, according to two of Britain's best-known former racers.
Martin Brundle and Damon Hill both agreed that the six-time champion is a relentless and deserved record-breaking success story, Brundle saying he felt privileged to witness his feats.
Hamilton last Sunday became the sport's most successful driver when he claimed a record 92nd win, moving one clear of seven-time champion Michael Schumacher's 14-year record of 91 wins.
Hill, the 1996 world champion, believes Hamilton needs to be challenged by and beat another driver of the same calibre if he is to silence the doubters.
"There's a risk that Lewis's achievements will be measured against the intensity of his competition," said Hill, who had to beat Schumacher to win his title.
"Mercedes have totally dominated this era and Lewis is not challenged."
Brundle said he would not be surprised if Hamilton won 10 championships.
"I'm not sure we ever thought anybody would approach, let alone surpass, Michael Schumacher's tally of 91 victories," the commentator told Sky Sports before adding "and I think there's a long way to go yet".
Brundle added that Hamilton, like Schumacher, says he is not interested in statistics and league tables, but did this only to deflect pressure.
"I could see Lewis aiming at something like 10 frankly and a long way north of 100 victories."
Hamilton will be seeking a 93rd victory to help Mercedes seal an unprecedented seventh consecutive constructors title at this weekend's Emilia Romagna Grand Prix amid much speculation about his future.
He is out of contract this year and Formula One is heading towards a likely salary cap for drivers in 2023.
Reports have suggested that Hamilton wants to improve on his current deal, claimed to be worth around 40 million euros per season while Mercedes want to cut costs.
Team boss Toto Wolff is also out of contract this year, but like Hamilton has said he wants to stay with the team – and would much prefer to secure the champion on a multi-year deal instead of a one-year extension.
Hamilton has a lead of 77 points ahead of nearest rival and Mercedes team-mate Valtteri Bottas, who has agreed already to stay with the team next year.
As the F1 circus returns to Imola, for the first time in 14 years, Hill and Brundle will have memories of the tragic 1994 San Marino Grand Prix stirred.
That weekend saw the deaths of Hill's close friend Austrian Roland Ratzenberger in qualifying and his Williams team-mate Brazilian Ayrton Senna during the race.