Two years ago, Hawkeye technology determined that, on average, Rafael Nadal's forehand produced 3,391 revolutions per minute. Jack Sock, with his extreme western grip, was second at 3,351. The two also had the fastest average forehand speed, 77 miles per hour, and are generally considered to have the fastest racket-head speed when swinging at the ball.
When the numbers crunchers at this year's Australian Open rolled out the average numbers for 2012-16, Sock had opened up the gap, posting an 86.33-mph forehand. Rafa was well back at 79.32. At the Miami Open, Sock had a more modest lead, 3,281-3,245 and 80 mph to 77.
But that edge did little to help Sock on Wednesday night in Miami as the world's two most fearful forehands met in the quarterfinals of the Miami Open.
The No. 5-seeded Nadal artfully eliminated Sock 6-2, 6-3 and will next play Fabio Fognini in Friday's semifinals.
On this occasion, it was Rafa who exhibited a greater control over his forehand and his nerves -- and a vastly better backhand.
Relentlessly attacking Sock's weaker wing -- a game plan that has worked historically against a guy named Roger Federer -- Nadal has now won all three of his matches against Sock. Tactically, he sent more serves toward Sock's forehand, which had to surprise him. Nadal's defense throughout the 83-minute match was vintage.
"Yes," Nadal said in his on-court interview. "That's something, playing against top players, that makes the difference. I was able to win the important points."
This is Nadal's seventh semifinal run in 13 attempts -- the most times he has ever played a tournament without managing to win it at least once. Rafa, who turns 31 during the upcoming French Open, fell to the resurgent Federer in the fourth round at Indian Wells, while Sock was his victim in the semifinals -- his first career ATP Masters 1000 appearance in the final four.
Rafa could meet Federer in a potentially delicious final -- an encounter that would be their third meeting of the young year.
There's still a lot to like about Sock, who is off to the best start of his career. He entered Miami with a career-best No. 17 ranking and will rise to at least No. 15 when the new rankings come out Monday. The only younger players ranked ahead of Sock are 21-year-old Nick Kyrgios and 23-year-old Lucas Pouille.
Sock and Nadal, each with 18 match wins, lead the rest of the ATP World Tour field. Sock came in as the No. 7 player in the year-end Race to London standings. He's now 18-4 and, despite the loss to Rafa, has beaten four of the past six top-10 players he has played.
This was Sock's fourth straight quarterfinal appearance in an ATP Masters 1000 tournament going back to Shanghai and Paris last season -- the first American to do so since Andre Agassi in 1999. He's also playing in Thursday's the doubles semifinals with Nicholas Monroe.
Essentially, Sock will do anything not to hit a backhand, a stroke he has nonetheless worked hard to improve, especially crosscourt. The speed and spin on his forehand take time away from opponents, but it also requires more time to execute. This is one reason Sock -- and Rafa, too -- is so comfortable on clay.
Even when he lost the No. 1-ranking for American men to John Isner in the final regular-season tournament of 2016, it seemed obvious Sock was destined to become the United States' next top-10 player.
It has been six years since it happened last. Mardy Fish was No. 8 in 2011.
Entering the season, Sock found himself bunched in a group with fellow Americans Isner, Steve Johnson and Sam Querrey. Now Sock, a few years ahead of a talented pack of 19- and 20-year-olds, has separated himself.
But while that's a worthy accomplishment, it's not going to get him past the likes of Rafael Nadal -- not yet anyway.