And it's close to becoming a lock that world No. 5 David Ferrer will hold his current place, too, fending off challengers such as Tomas Berdych and Jo-Wilfried Tsonga.
If the top four are as close to a sure thing as it gets in professional sports, is there room for that level of stability to be expanded to five?
Ferrer has had a career year with two Grand Slam semifinals made and five titles won, a feat no one ranked below him has achieved. He's won tournaments on three different surfaces—grass, clay and hard—this year. The only other player to pull that off in 2012? None other than world No. 1 Federer, which is some prestigious company to be in.
Not only that, Ferrer—with the prolonged absence of Nadal from the tour—has led Spain into the Davis Cup finals for 2012.
This week, he is the top seed at the ATP World Tour stop in Kuala Lumpur, and you have to like his chances to add another first-place trophy to the mantelpiece.
A number of factors have brought Ferrer to this point in his career at the age of 30. For one, he's extremely fit and has the capability to wear out a number of foes. Consistency is another factor: Unlike his more powerful peers such as Berdych, Tsonga and John Isner, Ferrer's game is less likely to break down and he avoids some of the more streaky tendencies players go through.
But Ferrer isn't just a scrambler out there relying on fitness and steadiness. He's capable of generating plenty of power off his groundstrokes, even though it might not look as easy as it does for Federer or Djokovic.
Ferrer has slipped out of the No. 5 spot this year, and it looked like he was going to be in a back-and-forth battle with Tsonga for it. However, as is his tendency, Ferrer fought to get it back and it looks like he'll finish 2012 there.
With his level of play at an all-time high, perhaps it's time to expand the "Big Four" to "Five" as Ferrer doesn't seem to be going anywhere any time soon.