In the QFs, Rafael Nadal won with a legend’s guile, and Carlos Alcaraz with a teenager’s moxie. How will they stack up in their all-Spanish clash of generations?

Over and over, Cam Norrie hit shots that looked like they were going to be winners. Over and over, I kept thinking, as the ball hung in the air and neared its second bounce, ‘There’s no way Alcaraz can run all the way across the court and get there in time.’ Over and over, Alcaraz kept running all the way across the court and getting just in time.

As the 18-year-old continued to defy time and physics and gravity and the limits of human speed against Norrie on Thursday night, I kept thinking about another time and place, and another 18-year-old player. The time was 2005, the place was Roland Garros, and the player, of course, was Rafael Nadal. Watching Rafa in his debut French Open, I can remember thinking, as an opponent’s shot hung in the air 20 feet away from him, ‘There’s no way he can run all the way across the court and get there in time,’ only to watch Rafa get on his horse and do exactly that.

It wasn’t that Nadal at 18 was the fastest player on tour. It’s just that I’d never seen anyone even try to make those types of gets before. The same goes with Alcaraz at 18: There’s no shot right now that he doesn’t believe he can track down, and most of the time he’s right. The torch of exuberant willfulness looks like it’s about to be passed from one Spaniard to another.

“I think he’s unstoppable in terms of his career,” the 35-year-old Nadal said on Thursday. “He has the passion. He’s humble enough to work hard. He reminds me of things when I was a 17- or 18-year-old kid.”

WATCH: Alcaraz ousts Norrie to set up Indian Wells semifinal with Nadal

The two Spaniards won back-to-back matches in Indian Wells on Thursday that were both perfectly age appropriate.

Nadal beat Nick Kyrgios with the smarts and self-belief and total lack of panic that comes with having won more than a thousand matches over nearly two decades—as well as 19 straight this year so far. For the first nine games, he was out-hit and out-played. Then, with Kyrgios serving for the set at 5-4, Nadal suddenly won a point at net, returned a 140-m.p.h. serve, hit a forehand pass, and broke serve. In the third set, Kyrgios again had the momentum, but Nadal again found a way to take it back. This time—for the first time in the tournament—he moved up to the baseline to return serve, threw Kyrgios off, and quickly broke.

In edging past three much younger opponents this week—Sebastian Korda, Reilly Opelka and Kyrgios—Nadal has had to play heady, measured, veteran tennis.

“A good dynamic and winning matches in a row,” Nadal said, “[is] when this kind of stuff happens.”

If you’re an NBA fan of a certain age, watching Nadal this season will bring back memories of watching Michael Jordan in the latter stages of his career. He couldn’t dunk from the foul line or score 63 points in a play-off game anymore, but none of his younger opponents knew as much about how to win as he did.

Watching Alcaraz, on the other hand, is like watching Jordan in his early 20s, when he would dribble between his legs five times before blowing past whoever was guarding him, and then do it again and again. Norrie, the 12th-best player in the world at the moment, was playing near the top of his game on Thursday. He attacked at the right times, he hit penetrating shots, he ran everything down, and he never gave up. And he lost 6-4, 6-3. Alcaraz just hit the ball too hard and too accurately, from both wings, and moved too well. The win moved him into his first Masters semifinal, but while he was on court, he looked like the best player in the world. Like Nadal in 2005 or Jordan in 1984, Alcaraz appears poised to take the sport to the next physical level.

Nadal and Alcaraz don’t play exactly the same way. Rafa has always built points patiently and played as much defense as offense. Alcaraz, who likens his style to Roger Federer’s, is more of a classic power-baseliner. They played once before, on clay in Madrid last year, and Rafa won 6-1, 6-2. But Alcaraz’s game may be more of a natural fit on hard courts than Rafa’s, and this match should be much closer. Again, Nadal may have to weather an early storm of winners, and find ways to defuse and frustrate a younger, offensive-minded player.

“I think you saw my level,” a confident-sounding Alcaraz said when he was asked how he might fare against Nadal. “I think I’m playing a good level in this tournament.”

Whatever happens, both guys sound like they’re looking forward to this clash of generations, and clash of countrymen.

“I’m going to have fun and enjoy every single second in the match,” Alcaraz said. ‘It’s a very special experience for me.”

“I am super happy,” Nadal said, “it’s going to be a great rival for now and for the next couple of months, without a doubt. But thinking and being selfish, it’s great, honestly, to have such a star from my country, because we, for the tennis lovers, we’re going to keep enjoy an amazing player fighting for the most important titles for the next, I don’t know how many years, a lot of years.”

The torch of Spanish tennis, and willful exuberance, won’t be passed in one match. For tennis fans, the longer it takes, and the more we get to see Nadal and Alcaraz striving as hard as they can as opponents and colleagues, the better.