Hard to remember a more significant Slam than the 2017 Australian Open

MELBOURNE, Australia -- There may have been other Grand Slams as historically significant and downright astonishing as the 2017 Australian Open, but it's hard to remember any after a weekend in which Serena and Venus Williams, then Roger Federer and Rafael Nadal, unexpectedly reprised their rivalries in the championship matches.

Federer's thrilling five-set win against Nadal in Sunday's men's final closed out a tournament in which the greats reminded us why they became legends and the underdogs showed us the hope that still drives them to play isn't always delusional. It dignifies them.

An unheralded player from Uzbekistan, 117th-ranked Denis Istomin, came here and pulled off the biggest win of his career at age 30, proving that Novak Djokovic isn't invincible. Then a few days later, Croatia's Mirjana Lucic-Baroni, a prodigy at 15 who at one point left the tour because of an allegedly abusive father, re-emerged and tore all the way to her second career Slam semifinal 18 years after her first. Lucic-Baroni was so emotional before she served out her last game against Karolina Pliskova in the quarterfinals that she put a set of rosary beads around her neck for strength, and collapsed on the court crying after her win was complete.

Two weeks is a long time for an athletic event, but the beauty of tennis' Grand Slams is that it is enough time for athletes to recalibrate themselves, reveal themselves, acquit themselves, surprise themselves, and in the case of Federer, Nadal and Venus, put some wonder back into their personal stories. All while Serena cemented her claim as best ever by winning her 23rd Grand Slam title here, a record for the Open era. All four of those legends are on the back half of their careers, and we thought we already knew the basic outline of the ending. Turns out we were wrong.

"I feel I played very well this week, pulled a lot of things out of my pocket," said Venus. "I got more stuff in my pocket."

One of the takeaways here is even 36-year-old Venus, not just Federer and Nadal, may yet contend for more Slam titles. Somehow she's getting better results in the past two years than she did from 2012 to '14, when she was first diagnosed with Sjogren's syndrome.

Serena offered her explanation why after beating her older sister 6-4, 6-4 for the title Saturday night. Serena said it has become emotionally easier for her to play Venus all these years later, "but physically, absolutely not. ... It's a whole different ballgame.

"I hit some big serves that would be aces 99 percent of time. Not against her."

Nadal and Federer were fighting their own droughts at majors. In the past year, injuries dogged both of them. Federer is 35 and Nadal was said to be an "old" 30 because of too many injuries and miles on his legs. Each took a long break to heal, and they returned here playing as well as they did three or four years ago. Federer's shot-making skills ran Tomas Berdych off the court and later had the stamina to repel Kei Nishikori and Stan Wawrinka.

Nadal is always a different customer for Federer to handle. As tennis analyst Mary Carillo perfectly put it, "When Roger is playing at his luminous best, he has no need to worry about the other side of the net against anyone else.

"But if he is playing Nadal, even his best is often not enough."

Multiple Grand Slam champ Mats Wilander was one of the few folks who said he wasn't rooting for another Federer-Nadal final; he preferred to see some new faces contending for titles here. But everyone -- even him deep down -- kinda, sorta got what they really wished for.

Grigor Dimitrov, now 25, said last year that he was recommitting to his career, but never did the results look as terrific as the nearly five-hour semifinal battle he had with Nadal.

Top-ranked Andy Murray was upset by Mischa Zverev on the same day women's No. 1 Angelique Kerber went down to an overpowering CoCo Vandeweghe. While no one was surprised when Zverev returned to anonymity with his quarterfinal loss to Federer, Vandeweghe's back-to-back wins over Kerber and defending French Open champ Garbine Muguruza before the American lost to Venus in the semis stamped her as someone to watch going forward.

But in the end, it was once again Serena and Venus, Nadal and Federer, all playing on the final weekend together for the first time since 2008.

"Let's enjoy this," Nadal said, "because probably won't happen again."