O'Sullivan, 38, will be looking to equal Davis's record of six world titles when the Dafabet World Championship starts in Sheffield next week, while Stephen Hendry's record of seven titles is also within sight.
"He is fitter and has more talent than anyone on the tour," Davis is quoted as saying by the Daily Mail.
"He's actually the one, not me or Stephen, who is set to push the boundaries of winning world titles in his forties.
"No-one has got close since Ray Reardon. Maybe he could be first of today's players to win a world title at 45."
The tournament gets underway on Saturday.