Rafael Nadal not yet ready to concede to next generation

— -- MELBOURNE, Australia -- In elite tennis, generations are measured in years, not decades.

The lifespan of the great champions is fleeting, their entrances and exits moments to savor. And when two of those upward and downward trending vectors converge, history happens.

In 2001, a 19-year-old from Switzerland stunned four-time defending Wimbledon champion Pete Sampras in the fourth round. Who knew then that Roger Federer would one day equal Sampras' standard of seven Wimbledon titles?

Likewise, a sturdy 19-year-old from Mallorca took down the still-dominant Federer in the semifinals of the 2005 French Open. Rafael Nadal would go on to win nine titles at Roland Garros.

On Saturday, Nadal ran into a 19-year-old phenomenon named Alexander Zverev -- and their Australian Open collision required 4 hours, 6 minutes to sort out.

Rafa, at the age of 30, sampling some of his classic performances, survived 4-6, 6-3, 6-7 (5), 6-3, 6-2.

This was not terribly surprising, for Zverev has been on the radar for more than a year now. But in the end, although this result was conclusive, it was far from satisfying.

That's because in the crucial fifth set, after a long rally with the score 2-2, Zverev's legs began to cramp. Whether it was physical or mental -- or both -- didn't matter. The fight seemed to leak out of Zverev, and Nadal won going away.

"I lost my service game I think because of that a little bit," Zverev said of the cramps. "So yeah, those are a big reason for it."

He will take valuable lessons from this experience, just like his previous eventful match with Nadal.

A year ago at Indian Wells, California, Zverev had a chance to put Rafa away in the third set and, with an open court beckoning, blew an easy volley on match point. Nadal, champion that he is, won 15 of the last 16 points, and Zverev would have to wait for his first top-10 win.

Nadal acknowledged afterward that he might have defeated a soon-to-be star. He reiterated this idea before Saturday's match.

"He has a big chance to become the future world No. 1, no?" Nadal observed. "He has all the shots: great serve, great forehand, great backhand, everything. He's a complete player.

"I need to put a rhythm very, very high to try to not let him in comfortable positions. That's what I'm going to try."

And "try" was the operative word.

Zverev, a willowy 6-foot-6, 189-pound athlete, has an exceptional wingspan and moves fluidly for someone so large. And, unlike a lot of youngsters, he actually doesn't mind hitting a backhand.

"Yeah, I am close," said Zverev, who turns 20 in April. "I showed it a few times last year. That was a great fight. There's a lot of positives in this match. I think he's one of the fittest tennis players in the history of the game.

"I could have won, but I'm fine, actually."

Think about how far this teenager has come, and how fast.

His 2016 season began right here, with a sobering 6-1, 6-2, 6-3 loss to Andy Murray. But in that score line was a modest microcosm of the season to come. Zverev lost to Dominic Thiem three times before running him down in Beijing in the fall and beat Federer in the semifinals at Halle, Germany. Zverev won his first title in St. Petersburg, Russia, taking down Tomas Berdych and Stan Wawrinka.

Zverev has already defeated Federer in 2017 -- in three tiebreakers -- in an exhibition at the Hopman Cup in Perth. So he has competed with the two most accomplished players of their generation in a narrow span of 17 days.

This is a curious time for Nadal, who again finds himself in comeback mode. He had to pull out of Roland Garros last year with a wrist injury and missed Wimbledon altogether.

Make no mistake, Rafa is still capable of taking your breath away. In the midst of his fourth-set resurgence, he produced a marvelous, leaping, twisting, overhead backhand and punctuated it with a classic scissor-kicking uppercut.

After losing three consecutive five-set matches, this was a resounding win. It's also worth noting that Nadal reversed another trend: Until Saturday's victory, he had lost six consecutive Grand Slam matches after losing the first set. And this was Rafa's first win over a top-25 player in a major in two years.

Going forward, he will be buoyed by this effort, beginning with Monday's fourth-round meeting with No. 6 seed Gael Monfils.

It took Zverev all of five minutes to lay down the challenge. He broke Nadal in the opening game with a lovely stretch backhand, punctuated by a clenched fist and an impressive glare.

And so, for now, the so-called torch remains in Rafa's muscular hands. But for how long?

"He's a player that has an amazing potential," Nadal said. "He's already one of the best players of the world. But he can be even better. He can be fighting for the most important things.

"So I think he will do it."