Lewis Hamilton is "on the same level" as Formula 1 legend Ayrton Senna, says the late Brazilian's former team-mate Gerhard Berger.
The Austrian said he had always regarded Senna as a class apart but now considered Hamilton, 34, on a par.
Berger said: "Everybody asks me: 'How do you see this driver against Ayrton?'
"And I always, in all the years, say: 'I don't see anybody near to Ayrton.' But Lewis is [now] the first driver I put on the same level as Ayrton."
Berger, 59, was team-mate to Senna at McLaren from 1990-92 and became a close friend.
Senna, who many regard as the greatest driver in the history of Formula 1, won 41 of the 161 grands prix in which he competed, three world titles and 65 pole positions before he was killed in a crash at the 1994 San Marino Grand Prix.
Mercedes driver Hamilton, for whom Senna was a childhood idol, has won 75 of his 232 races so far, five world titles and an all-time record of 84 pole positions.
Overall, however, Berger said he still held Senna in higher regard, when also considering his charisma and character.
"The comparison? I see still Ayrton winning the game because in the end Ayrton was such a charming guy and a personality," said Berger.
"And obviously if someone loses his life and stays with us in the way of a legend, it's always something special.
"But I try to see it from a performance point and from a performance point, Lewis is going from one pole position to the next one and Lewis is going from one race win to the next one. Just like Ayrton did."
Berger said there were more ways of measuring greatness than just statistics.
"I go more by feeling and watching, and for me - and there were great champions like Nelson Piquet, Niki Lauda, Alain Prost, Michael Schumacher - there has always been one above: Ayrton," he said.
"And now Lewis I see in the same league."
Berger said Hamilton was "outstandingly fast", made fewer mistakes than his rivals and knew when to be patient.
"It looks like he's just running the game in such a good way that he's unbeatable at the moment," he said.
"Yes he's in the best car and best engine, but he also is the best. By far the best man at the moment."
He said Hamilton had a good chance of breaking Schumacher's records of 91 grand prix wins and seven world titles.
"I would like to protect Michael's success because it's such a tragedy, it's so sad to see these things," Berger said, referring to the 2013 ski accident that left the German with severe head injuries, since when he has not been seen in public.
"But when you put this all out for a moment, then Lewis Hamilton is a very special driver in all the time I have watched and have been in Formula 1."