If you didn't know any better, you could be forgiven for thinking Roger Federer's most frequent opponent this year was some garden variety journeyman, not his legendary rival.
On Sunday in Shanghai, Federer beat Rafael Nadal in straight sets, the Swiss' fifth straight win in this rivalry.
Sure, Federer might not have enough time to catch up with Nadal in the head-to-head statistics. After all, Nadal still holds a significant 23-15 lead. But Federer is making the most of his career renaissance, with four of those five wins coming this season.
They're the top two players in the world; Rafa is No. 1 with 10,465 points, a lead of nearly 2,000 points (the equivalent of winning one Grand Slam) against Federer.
Federer could pull closer next week at the Swiss Indoors, especially considering Nadal pulled out of the event to take precautions with a wonky knee.
Whatever unfolds the rest of 2017, it's clear Federer, 36 and five years older than Nadal, has figured out the M.O. to take his Spanish foe down.
Which leads us to these questions:
What is different about this season?
To borrow and retool that famous political slogan, "It's the surface, stupid!" Federer's streak was created on hard courts. This surface not only favors his game, it seems to be getting incrementally faster with every passing month. And the faster the courts play, the more they suit Federer's retooled, aggressive fame. Nadal isn't an excuse-maker, but he also won't shy away from expressing his honest opinion.
After the Shanghai final, he told his ATP handlers: "There is room to improve for me, and I'm going to try. But the conditions here were much better for him than for me, being honest."
The key match in Federer's revival was the Australian Open final. Few expected that Federer could bounce back from a 3-1 fifth-set deficit against a man renowned for his stamina, strength and ability to grind down opponents. But on the quick courts, Federer was able to force the action. His offense prevailed, setting the tone for the next three meetings.
But that was just the first half of a 1-2 punch. The other was Federer's decision to forgo competition on dirt. He didn't play a single clay-court event this year, not even the French Open. A cynic might surmise that after surprising Nadal with that great comeback in the Australian Open final, Federer saw no reason to allow Nadal to get traction in their rekindled rivalry. That's probably taking it too far, but lack of participation on clay is probably the single greatest reason Federer has won five in a row.
Are there new technical or strategic dimensions to Federer's new superiority?
Call it the law of unintended consequences. Federer probably was thinking more about advancing age and Novak Djokovic's stranglehold on the game than Nadal during all that time the Swiss took off during the second half of 2016. But the new emphasis he placed on aggressive play and offensive strategies for 2017 has paid off in a big way against Nadal.
The main reason is simple. Nadal remains the most defense-minded of the Big Four players, ever vulnerable to superior offense on fast surfaces. Federer's dazzling volley, his effective slice, that ability to hit his spots with his serve -- it all keeps Nadal off-balance and guessing. Federer has the precision to exploit the depth at which Nadal likes to set up shop on the court.
As Brad Gilbert noted recently, Federer's commitment to hit his backhand, to not back down from his one vice, has opened up all kinds of opportunity. No longer can Nadal pick on that wing. Fed's backhand, and the confidence he now has in that shot, has been the single biggest factor in the turnaround.
Remember all those French Opens when all the talk was about how Nadal was in Federer's head? Well, the two have switched residences.
What's Nadal's issue?
That's an interesting, unavoidable question, well buried in Nadal's outstanding 2017 record. Nadal can still get the best of anyone else, often with ease. But the way Federer's been beating him is difficult to explain, even in light of Federer's resurgence.
The most persuasive evidence for that is the routine way he has won their past three meetings. He allowed Nadal no sets, and in Shanghai denied him any break points. Federer lost just eight points on serve in the match. Good as Federer is, that is just very un-Nadal-like.
Unlike Federer, Nadal's resurgence in 2017 came in the wake of a period when he suffered from a visible, sometimes dreadful loss of confidence. He experienced a slump that was as much mental as it was physical. That crisis may have left Nadal's playing psyche with some lingering damage that Federer, if no one else, can access.
What lies in the immediate future for this rivalry?
Nadal is up against it. Federer could not have boxed him into a more difficult corner if he planned it. The two are next scheduled to meet in at the Paris Masters in a couple of weeks. Then, barring injury, both will be in the ATP World Tour Finals, the year-end event that Nadal has never won -- and where Federer is the six-time champion.
The chips all seems stacked in Federer's favor to win again if they are to meet, but the deficit in their ranking points might be too much for Fed to overcome. Still, one final push (and some luck) and we could see the final encounter of the season not only determine the World Tour Finals, but the No. 1 ranking. That scenario happened a year ago between Andy Murray and Djokovic.
It seems only fitting that one match with so much at stake between the other two Big Four members close out 2017.
How does this run affect the GOAT debate?
Yes, we saved the most pressing question for last. Times are getting tough for the vocal minority arguing that Federer can't be the greatest of all time if there's a player in his own generation that he cannot consistently beat.
All these triumphs not only highlight Federer's dazzling offense and fast-court expertise, they also underscore Nadal's shortcomings in those departments. Before 2017, Federer was never really able to dominate Nadal -- at least not in a way you could quantify. But the present trend suggests that Nadal has no solutions for what Federer brings on hard courts. And since any future meetings on clay will be few -- if any -- you'd have to guess than Federer has a good chance to cut his head-to-head deficit even further.
And if he does, Nadal will remain the King of Clay but Federer the Master of the Tennis Universe.