"I think we're living in what history will say is the golden age of tennis," said the American former world No 1. "I mean, you're not guaranteed a rivalry in sports, no matter how good you are."
Let alone such a rare three-way rivalry - and now four with Andy Murray breaking through at last year's US Open.
Agassi noted that in generations past the sport enjoyed special two-man rivalries including his own with Pete Sampras in the 1990s and early 2000s and when Bjorn Borg and John McEnroe reigned in the 70s and 80s.
"(Jimmy) Connors was involved in that equation and that's kind of the closest time where we've ever had what we're staring at now - and even that didn't really live up to what we're seeing in front of our eyes," Agassi said.
"We're talking about three guys that you could really make the argument have raised the standard of the game and potentially you have three guys that could be argued as the best of all time, pending Djokovic's upcoming year.
"You're looking at Federer, Nadal and Djokovic. So if he (Djokovic) could put together his best tennis at the right time this year, you're talking about three of the greats in one generation. It's remarkable.
"And certainly Murray is on the front end of a lot more accomplishments. He has obviously got longer to go to be in that discussion, but to break during a time when you have these three sort of suggests that he is going to have his time as well.
"So I think it's remarkable. But the game always improves when you think it can't, and it has.
"They've raised the standard."
- AAP