Both players have had to adapt, had to overcome recent difficulty, to get to this point. Nadal arrived in Melbourne with low expectations, having taken a hiatus from the tour after last fall’s United States Open, where he withdrew in the semifinals, citing a leg injury. In November, he had ankle surgery.

Dogged by his injured elbow at last year’s Australian Open, Djokovic was routed in the quarterfinals by Hyeon Chung, a South Korean ranked No. 58 at the time. That loss was one of a batch of stunning upsets he suffered in major championships after winning the French Open in 2016. Plenty of questions were swirling around him at the time. He often wore a hangdog, puzzled look on his face during matches, where once there had been nothing but ice-cold surety.

Would he ever return to form?

But then, last summer, after elbow surgery and a remodeling of his priorities and his coaching team, the old Djokovic emerged. His health returned. So, too, did his steel-trap resolve. He won Wimbledon, beating Nadal in a five-set marathon that Djokovic credited here with giving “a different, more confident self.”

Later in the summer, he won his 14th Grand Slam at a sweltering U.S. Open, tightening his grip on the top of the men’s rankings.

Now he finds himself again in a Melbourne final, with a chance to repeat the glory of 2012, a chance for a 15th Grand Slam, just two behind the Spaniard’s haul of 17, within striking distance of Federer, who sits at 20 for most in a career.

At his postmatch news conference, I asked Djokovic to imagine a future conversation with his two children, who were not yet born seven years ago, and how he would describe that last epic Melbourne night against Nadal.

“How would I describe it?” he said, pausing before adding a touch of humor. “I’ll probably not have them sit down and watch it because I don’t like my children to watch TV that long.”