To mark the end of a record-setting 2019 season, wtatennis.com is counting down our picks for the best matches of the year.

Top 5 Grand Slam Matches of 2019:
No.5: Barty d. Anisimova, Roland Garros
No.4: Andreescu d. Mertens, US Open
No.3: Pliskova d. Hsieh, Wimbledon
No.2: S. Williams d. Halep, Australian Open

Wrapping up the countdown in the Grand Slam category at No.1 is Naomi Osaka's dramatic victory over Petra Kvitova in the Australian Open final, where the Japanese star survived a second-set swoon to clinch a second straight major, as well as emerge triumphant in a clash for the World No.1 ranking.

WHAT HAPPENED: In the first Grand Slam singles final of 2019, which had Naomi Osaka and Petra Kvitova facing off for the very first time in a battle for the Australian Open title, even more was at stake beyond the typical significance of a major championship finale.

Both players came into the championship match hoping to maintain undefeated records in Grand Slam finals. Osaka was also on a 13-match winning streak at Grand Slam events, having raced to victory in the previous major, the 2018 US Open, for her maiden Grand Slam title.

Kvitova, for her part, had triumphed in two previous Grand Slam finals, at Wimbledon in 2011 and 2014. Kvitova’s return to this stage of a major event was particularly poignant, as it was her first Grand Slam final since the gutsy Czech’s serving hand was severely injured during an attack in a home invasion in December 2016.

Moreover, an additional layer of importance was grafted onto an already momentous match, as the victor would directly leap to the World No.1 ranking, which would be the winner’s first time at the top of the WTA singles rankings.

With a tremendous amount on the line, the two power players rose to the occasion and combined to contest a gripping Australian Open singles final.

Osaka was initially on course for a hard-fought but straight-set win for a second consecutive Grand Slam title. Neither player was broken in the opening set, but Osaka pipped Kvitova in the tiebreak to claim the first set.

After falling behind 0-2 in the second set, Osaka then blitzed to 5-3, where she reached triple match point on Kvitova’s serve after an hour and a half of play. However, the steely Czech erased each of those chances, and pulled herself back to parity at 5-5.

Read the match report: Osaka clinches second straight Slam, No.1 ranking at Australian Open over Kvitova

An increasingly frustrated Osaka saw her error count rise, and Kvitova took full advantage, claiming four straight games from the brink of defeat to scrape out the second set, which ended with a double fault from the Japanese player.

Holding the momentum, 28-year-old Kvitova aimed to notch her first Grand Slam title away from the grass courts of London. Osaka, though, swiftly disposed of any disappointment as the deciding set kicked off, and the 21-year-old displayed a resilience which belied her youth, earning a crucial break at 2-1 with a backhand winner.

Kvitova would not be broken again, but the Czech could not eke her way into her opponent’s service games in the final set, where Osaka won nearly 90 percent of her first-service points and saved the sole break point she faced. Ultimately, the lone break proved decisive in a nearly pristine set by both, and Osaka clinched the classic, 7-6(2), 5-7, 6-4.

WHAT THEY SAID: “When you're practicing really hard practices, of course you want to dream about what you're practicing for,” Osaka said, during her post-match press conference. “I think for everyone, it's to win Grand Slams and to be No. 1. So, yeah, of course those were two very big motivating factors.”

“People were talking about being No. 1 if I win this tournament,” the champion continued. “I was able to accomplish that. But the ranking was never my real goal, it was just to win this tournament.”

Despite faltering to lose the second set from triple match point up, Osaka said that “it didn't really take that long” to refocus. “I felt like I didn't want to have any regrets.”

“I was a robot, sort of,” Osaka stated. “I was just executing my orders. I just did what I've been practicing my whole life in a way. I didn't waste any energy reacting too much. But then when it got towards the end, then I started realizing how big the situation was, so then I think I started yelling ‘C'mon’ again.”

Osaka also said that while her rise to two-time major champion might have seemed meteoric from the outside, “I'm aware of all the work that I put in. I know all the sacrifices that every player does to stay at this level. In my opinion, it didn't feel fast. It felt kind of long.”

Kvitova said the loss was “painful,” but “I don't think I played something really badly. I just think I should maybe go a little bit more aggressive [in] one or two rallies. I really fought back in the second set. I'm proud of myself in that case. And, yeah, the third set was just one break. That's how the tennis is.”

The Czech added that Osaka is a “really big player, as she showed in the results. Winning the US Open and Australian Open, it's an amazing achievement. Definitely, she is a great one.”

“I wanted to be back on my greatest level probably as I played before,” said the resurgent Czech. “I knew it will be very, very difficult because my hand, it's not 100 percent, and never will be. It's just how it is. I'm just trying to take maximum from the minimum. I feel great, I'm playing great tennis. I don't think that I could really imagine the time to be kind of this player again.”

WHAT IT MEANT: With a 14th consecutive Grand Slam match-win in the books, Osaka used her sweep of two consecutive major tournaments to reach the World No.1 ranking for the very first time, supplanting Simona Halep at the top spot. Osaka had been ranked No.72 just twelve months earlier.

A patch of inconsistency occurred following Osaka’s victory in Melbourne, as she went through two coaching changes and failed to reach the quarterfinals at the other three majors in 2019. After jockeying back and forth with Ashleigh Barty at World No.1 mid-season, Barty wrested the top ranking away from Osaka for good by year-end.

Nevertheless, Osaka finished the season on an extremely high note, ending a titleless streak since the Australian Open by hoisting trophies in Beijing and her hometown of Osaka during the autumn. Osaka finished the season at World No.3, the highest year-end ranking of her career thus far.

Kvitova matched her career-high ranking of No.2 following the Australian Open final, but she too failed to reach any Grand Slam quarterfinals after Melbourne. The Czech struggled with a persistent forearm injury that caused her to miss tournaments sporadically, including Roland Garros.

However, the Czech still finished 2019 with two titles, at Sydney and Stuttgart, and retained the year-end No.7 ranking for the second straight season, earning her seventh Top 10 finish in the last nine years. Kvitova joined Osaka at the year-ending Shiseido WTA Finals Shenzhen, where they met for the second time -- and Osaka claimed another tight three-set victory.