The two most feared and revered men on the tennis scene have only met one time this year, namely on the fast clay-court in Madrid where Rafael Nadal won in two close sets.
Are we finally in for another clash between the two players, who bring out the most emotion in the fans?
It would be only their third meeting in the second half of the season ever and universally welcomed among tennis fans across the globe.
Roger Federer has almost secured his spot in the semis in the World Tour Finals in the O2 Arena in London after two swift straight sets wins over David Ferrer and Andy Murray.
Yesterday, he completely dismantled Murray, the player who gave him a whopping defeat in Shanghai less than a month ago.
He's not home safe, but pretty much everything has to go wrong if he's not to be found in the semifinals on Saturday. Not least as he has a staggering 14-1 record against the man he is to meet tomorrow, Swede Robin Söderling.
Now it is up to Nadal to meet his part of the deal.
While Nadal struggled against Roddick in the first half of the match, he turned the match around in classic Nadal fashion to leave Roddick short of his second straight win against the Spanish World No. 1.
Roddick could have won the match in straights, and maybe even should have, but the longer the match went on, the more Nadal seemed likely to come out on top—as he did.
In an hour's time, he will be facing Novak Djokovic, whom he last faced, and beat, in the US Open final. Will he prevail?
I think it is pretty much a toss-up given what we've seen from them. Rafa hasn't yet shown US Open form, whereas Djokovic was dominating against Berdych (who've just beaten Roddick in straights).
That gives the edge to Djokovic, but one can never discount Rafa.
And I would be surprised if he failed to win any of his last two round-robin matches, which in turn gives him pretty good odds of advancing to the semis, which brings us one big step further towards a Rafa vs. Roger match.
It may come in the semi's, but I would certainly prefer it to be in the final. Either way though, we would be in for the 22 meeting between the two greatest players of our era.
And the winner? I don't dare to make predictions on this. Though Roger seems very much in-form, Rafa may have worn off the potential rust after three round-robin matches.
The low bouncing relatively slow hard-court seems to give both players an advantage against the others tricks:
Rafa's forehand won't be bouncing as high to Federer's backhand, but Federer will have more difficulties shooting winners past Rafa's superb defence as the court takes a bit of the pace.
And Rafa has had the upper hand in six of their last seven meetings. Five of those were on clay though and only one on hard court (Australian Open), so it is no definitive guide.
Rafa is looking to add the one important remaining trophy to his already more than impressive resume. Federer is determined to end his worst season since 2002/03 on a high note and prove that he is by no means done yet.
In any case, let's hope for both of them to advance so we can get another one of those epic encounters, while both players are near their peak.