But last night, McEnroe was talking about the other, more rugged half of the sport’s most famous modern rivalry: Rafael Nadal. Nadal had just beaten Tommy Robredo, the Spaniard who had dismissed Federer in straight sets the round before.

Unlike Federer, Nadal has more frequently conjured up images of sweaty, fast-and-loose iconoclasm and brute force among sports journalists. In the years since his inaugural French Open victory in 2005, and most noticeably in the first few years after, he drew comparisons to pirates, cavemen, bulldogs, bulls, bulls, more bulls, bulls in china shops, bulls in Federer’s china shop, and, um, “Apaches.”

So I wondered at first if McEnroe had somehow forgotten which player he’d just watched, or if he’d maybe meant Leonardo the Teenage Mutant Ninja Turtle (same headwrap!). But his offhand remark actually sheds light on a truth about Nadal that’s been somewhat underappreciated until recently: He may not be the magical athlete-artist Federer is (or—gulp—was), but he’s the Leonardo da Vinci of the sport in that he’s a whiz kid—a tennis brainiac.

Leonardo da Vinci, after all, wasn’t just an artist. Like Albert Einstein, he was a scientist, too—and an engineer. He spent years doodling up designs for machines that could make a human fly; five centuries later, when scientists built his imaginary contraptions out of modern materials, some of them actually flew. Da Vinci was a tinkerer with an intuitive comprehension of how things worked—and the same could be said of Nadal. Despite the mentions of Nadal’s “baseline bashing” and “extremely physical style of play,” it’s come to light in recent years that Nadal is unquestionably one of the best thinkers in the game of tennis, with a terrifyingly deft understanding of its science and strategy.

Last night, McEnroe instructed all the junior players watching the broadcast to closely observe Nadal’s play because, by subtly identifying his opponent’s movement patterns and adjusting and re-adjusting his service motion and returns accordingly, he was putting on what McEnroe called “a clinic” in shot placement. (The importance of being able to analyze and respond to an opponent’s play during a match shouldn’t be underestimated: Earlier this week, as The New York Times’ Geoff MacDonald noted, Federer made his earliest exit from a Grand Slam in 10 years because he failed to readjust his game plan against Tommy Robredo in the fourth round.)

Gilbert and McEnroe also made mention last night of a 2011 New York Times video feature that delved into the physics of why Rafael Nadal’s lethal lefty forehand—sometimes affectionately known as the “fearhand”—causes so much trouble for his opponents.

The answer? Topspin. Nadal’s extreme grip on the racquet results in a rate of topspin twice what Andre Agassi’s and Pete Sampras’s were when they played. In layman’s terms, if you’re on the other side of the net when a tennis ball comes hurtling through the air spinning as quickly as a Rafael Nadal forehand shot spins, it will bounce in ways you did not expect a tennis ball to bounce, especially on clay—even if you’re used to playing guys who play like Agassi and Sampras. And your attempt to hit it back with control will likely fail. This isn’t just a quirk of Nadal’s game; rather, it’s a willful mastery of a strange, somewhat unnatural, and acutely effective technique.