Rafael Nadal reacts to losing to Roger Federer in the Australian Open final, explaining that he is back to playing at a high level and expects to have a great season. (2:37)

Rafael Nadal knew. He stood there on the trophy presentation podium, a stony expression on his face, forgetting even to applaud on cue as the tennis officials and sponsors plodded through their predictable speeches.

Rafa knew.

Roger Federer, the man standing beside him, had just pulled off a surprising, yet very Federer-like, stunt. Down 3-1 in the fifth set, with his legs wobbly and worked over twice already by tournament physiotherapists, Federer improbably rallied.

Dancing along the edge of disaster, he produced flashy winners and changed the course of the match. Suddenly, he leveled the score and reeled off the final three games to win the Australian Open 6-4, 3-6, 6-1, 3-6, 6-3, his 18th Grand Slam title.

Later, Nadal would have time to process it all, to extract the positives, which were numerous. He would say in his news conference: "It is not more than another important title for him, another important two weeks for me. Even if didn't finish the way that I wanted, it has been an important two weeks for me."

But in the immediate aftermath, Nadal, as gracious a loser as the game has known, understood the magnitude of the opportunity that had slipped away. How else to account for his hard visage, that uncharacteristic, faraway look in his eyes?

Nadal managed to focus when he accepted the runner-up trophy. His speech began mechanically, but slowly he regained his equilibrium. He talked about his injuries, told the crowd how hard he had worked to get healthy and promised to keep trying. He seemed to catch himself, realizing how long he was going on, and awkwardly halted, "Now I'm gonna let Roger take the trophy [and speak]."

Nadal's mind still seemed elsewhere. It might have still been in that fifth set. Had he managed to hang onto that break, the ensuing win might have been more than a game-changer. It might prove to be a history-changer, with Nadal rivaling Federer's Greatest of All Time credentials.

A win would have bumped up Nadal's head-to-head lead over Federer to a very persuasive 24-11. It would have left him ahead in Grand Slam finals 7-2. It would have closed Federer's lead in Grand Slam titles to 17-15, with Nadal's favorite, the French Open, coming up next. The GOAT debate certainly would catch fire and rage on.

Disappointing as the outcome was for Rafael Nadal, it was a much better showing than last year's first-round exit. SAEED KHAN/AFP/Getty Images

Now? It's Federer's planet -- everyone else is just hoping for a wild card.

That's business as usual, though, as Nadal well knows. He has labored in Federer's shadow for most of his life, even during those periods when he was cleaning his Swiss clock. Put it down to Federer's enormous appeal, which begins with his beautiful tennis.

Both men embarked on this fortnight after missing all (Federer) or most (Nadal) of the second half of 2016 with injury, but Federer and his exploits overshadowed Nadal and his own efforts. Granted, Federer at 35 is almost full five years older than Nadal. That's a very big difference, and likely to be a significant influence in five-set matches.

It's also true that Federer had minor knee surgery almost exactly a year ago, while Nadal had a bad wrist, but never had to go under the knife. What some forgot, though, is the slump Nadal slipped into starting in mid-2015 (he hadn't been in a Grand Slam quarterfinal until this week) and the excruciating struggle he visibly fought with his nerves in so many matches.

A tennis player's mental wounds may be self-inflicted, but physical ones are a different matter. Federer has been blessed. He was hampered by a bad back in 2013 but had never before undergone surgery. He didn't miss a Grand Slam tournament for 16 consecutive years, ending just last year when he skipped the French and then had knee surgery after Wimbledon.

Nadal, by contrast, has a history of injury-related absences dating all the way back to his second year as a Grand Slam player. He has missed seven Grand Slam events, five after he first won one in 2005. He was unable to defend the Wimbledon title he won in 2008 over Federer (in a match many call the greatest ever played). Nor was Rafa able to defend his 2013 US Open title -- or his finalist finish in 2011.

Last spring, Nadal's wrist was so badly hurt that he had to quit his quest for a 10th title at Roland Garros mid-tournament. The other day in Melbourne, he told the media: "Last year was tough. When you feel that you are playing very well and you have to go from Roland Garros without going on court. ... I remember myself crying on the car coming back to hotel."

Melbourne has provided Nadal with many occasions to lapse into tears as well. In 2012, he held a 4-2 lead in the fifth set, only to lose the historic 5-hour, 53-minute final to Novak Djokovic. Perhaps even more crushing: Nadal's back was visibly locked up on him for a good portion of the disappointing 2014 final against Stan Wawrinka. Then, too, Nadal was facing an opportunity to rephrase the GOAT debate.

Last year, Nadal simply ran into a buzz saw named Fernando Verdasco in Melbourne. "Being honest, last year I felt great coming here, but I lost in the first round," Nadal said. "So when that happened, is difficult to explain to you that I feel well. Being honest, that's the truth, no?"

The one title Nadal won in Melbourne does stand out, not least in the mind of his beaten rival. Federer still cites that 2009 five-set win by Nadal as perhaps the finest example of sustained, excellent shot-making by two men. It was a match that left Federer with tears streaming down his cheeks during the trophy presentation.

The shoe was on the other foot Sunday, and once again the difference came down to shot-making. As Nadal said, reflecting on the critical, final games of the fifth set: "The way that he played, he can put the balls in -- or not. And he put a lot of balls in, taking a lot of risks, and taking the ball very early, playing very fast. So then he had the success. Well done for him."

Once again, Melbourne has dealt Nadal a losing hand. But his feeling of rejuvenation seems justified, and springtime in Paris isn't far off.