Frankel will remain the top rated horse of all time whether he rounds off his career with his 14th win in 14 starts or loses in the Champion Stakes at Ascot on Saturday.
Form bible Timeform rates Henry Cecil's star a stone (6kg) better than Champion Stakes second favourite Cirrus des Aigles.
With the ground set to be soft which is not the odds-on favourite's preferred surface Cirrus des Aigles, who won the Champion Stakes last year, has gathered support.
But Jamie Lynch, Timeform's chief correspondent, said Cirrus des Aigles' rating of 133 (Frankel is 147) was similar to previous challengers, who had all tried and failed to get the better of Frankel.
"For Timeform, Frankel is the new benchmark for brilliance, and every other great thoroughbred that emerges in future will be measured against him - that's Frankel's momentous legacy as far as Timeform is concerned," Lynch said.
"Frankel has faced 133-rated horses previously, but only once has one run to that sort of figure in direct competition against him, namely Excelebration in the Queen Elizabeth II Stakes on Champions Day last year, which was Frankel's smallest winning margin (four lengths) since Royal Ascot 2011.
"The suspicion is that reigning Champion Stakes winner Cirrus des Aigles may have an even bigger performance in him on soft ground, in which case Frankel would need to be at his phenomenal best if he's to win in the manner we've become accustomed to."
Frankel received perhaps the greatest accolade when Timeform rated him 147 after his win in the Juddmonte International Stakes at York in August ending a 47-year reign by French legend Sea Bird, who ended his career rated 145, as the world's greatest racehorse.