A wheel to wheel race between Ayrton Senna and Lewis Hamilton would be "exciting".
That is the view of Felipe Massa, who in 2008 almost beat Hamilton to his first title.
Massa told the Salzburger Nachrichten newspaper said: "It would be exciting to see, no question. But we will never know who would be faster. In his time, Senna was almost unbeatable, especially in qualifying.
"In terms of speed, it's difficult to find another like him."
Massa's comments come after Senna's most famous team mate, Gerhard Berger, said Hamilton is on the same level.
Berger said: "I've always said 'I do not see anyone near Ayrton' but Lewis is the first driver that I see on the same level as Ayrton."