There are wins, and then there are those wins that mean more than an isolated moment. 

Take, for instance, Ashleigh Barty. As dominant as she was in 2021, her upward trajectory did not begin until three months into the season. 

Then there's Barbora Krejcikova. She was a solid player, but hardly a household name until Roland Garros, where she swept both singles and doubles. 

With that, here's a look at our most impactful matches from this past season. 

Barty sets tone for stellar season with win vs. rival Sabalenka

Ashleigh Barty’s 6-4, 6-7(5), 6-3 victory over Aryna Sabalenka in the Miami Open quarterfinals put Barty’s season on track for greatness, and it also resumed the rivalry between 2021’s two highest-ranked players.

After her 11-month hiatus, Barty started 2021 by winning the Yarra Valley Classic title in Melbourne. But the rest of her Down Under swing was underwhelming. She fell to Karolina Muchova in the Australian Open quarterfinals and Danielle Collins in Adelaide. Barty had not faced a Top 10 player in more than a year when she moved into her next event, in Miami one month later.

Sabalenka had been improving her consistency dating back to the end of the 2020 season. Coming into the quarterfinal match against Barty, Sabalenka had won 23 of her past 27 matches, all on hardcourt. Holding a 3-2 edge in her head-to-head against Barty at the time, Sabalenka was itching to add the World No.1 to her recent list of wins.

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However, Barty stared down and defeated the newest member of the Top 10 at the time without dropping serve and saved all seven of the break points she faced. That the match went three sets anyway was a testament to both Sabalenka’s rapid improvement and Barty’s determination to grit out her biggest win by ranking in more than a year.

“It was certainly the best level I’ve played for a long time, and especially over a sustained period,” Barty said on court after the win.

Spurred on by that victory, Barty beat Elina Svitolina and Bianca Andreescu (via retirement) to successfully defend her Miami Open crown from 2019, rejuvenating her season after stumbling down the stretch in Australia. Barty went on to finish the year with five singles titles, the most of any player in 2021.

The rivalry between Barty and Sabalenka extended into three-set championship battles during the clay-court season, defining that portion of the year. Barty bested Sabalenka in the Stuttgart final, but Sabalenka got revenge shortly thereafter in the Madrid final. Barty and Sabalenka have now won four matches apiece in their rivalry, with more tussles likely to come next year. -- Jason Juzwiak

Barbora Krejcikova wins French Open doubles title, completes Roland Garros sweep  

The night after winning the most important match of her young life, Barbora Krejcikova – not surprisingly – didn’t get much sleep. Replaying the points, reliving the swirling emotions of her 6-1, 2-6, 6-4 victory over Anastasia Pavlyuchenkova in the French Open final, the Czech Republic athlete was already tired when she woke up on a Sunday morning in Paris.

Maybe that was a good thing.

“I actually went really relaxed today when I went on court,” Krejcikova said later. “I was just trying to really support my partner.”

That would be Katerina Siniakova, with whom she added the Roland Garros doubles crown to her suddenly crowded resume. The No.2 seeds laid down a comprehensive 6-4, 6-2 win over Bethanie Mattek-Sands and 2020 French Open singles champion Iga Swiatek. They dropped only one set on the way to their third Grand Slam doubles title.

The victory established Krejcikova as the most well-rounded player in the game today.

The last player to win both titles at Roland Garros was Mary Pierce in 2000; the most recent one to do it in a major was Serena Williams at Wimbledon in 2016.

“I’m really thankful to [Siniakova] that she was there, that she was standing next to me,” Krejcikova said afterward. “It felt a little bit easier than yesterday.

“I’m just really happy that we have another title, and looking forward we’re going to continue with our cooperation in Wimbledon and also for the Olympics. I hope there’s going to be a bright future for us.”

As it turned out, the Czech pair would emerge from Tokyo with the Olympic gold medal, defeating Belinda Bencic and Viktorija Golubic 7-5, 6-1.

Bencic, who won Olympic gold in singles and silver in doubles, Elise Mertens (ranked No.4 in doubles, No.21 in singles and winner of two majors) and Aryna Sabalenka (ranked No.2 in singles and won the Australian Open doubles with Mertens) were the players who came closest to approaching Krejcikova’s impressive versatility for 2021.

She would go on to become the only player to qualify for both singles at doubles at the WTA Finals in Guadalajara, Mexico. She and Siniakova won the title there, too, besting Hsieh Su-Wei and Elise Mertens 6-3, 6-4.

Krejcikova finished the season ranked No.2 in doubles and No.5 in singles after achieving a career-high No.3 in early November. -- Greg Garber

Anett Kontaveit wins Moscow title en route to dominate end to season 

Coming out of the BNP Paribas Open, Ons Jabeur looked on her way to checking off another historic milestone for Arab tennis. The Tunisian's strong run to the Indian Wells semifinals, which she booked with a straight-sets win over Kontaveit, guaranteed she would become the first Arab player to rank in the Top 10 on either the WTA or ATP Tour. It also boosted her to No.9 on the Porsche Race to the WTA Finals, firmly in position for the final qualifying spot for the WTA Finals with two weeks remaining in the regular season.

Well, at least we thought it was firm. To overtake Jabeur, Kontaveit would have to run the table and win back-to-back tournaments - a feat she had never accomplished in her career - and reel off 10 consecutive wins.

Kontaveit would do just that, winning 20 of 21 sets to edge Jabeur and make history of her own, becoming the first Estonian to both rank in the WTA Top 10 and qualify for the WTA Finals. Statistically it sounds like Kontaveit rolled through Moscow and Cluj-Napoca. But Russia's Ekaterina Alexandrova was a handful of points away from writing a different chapter.

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Playing on home soil, the 27-year-old was in the middle of a torrid run of her own in Moscow, tallying wins over Jabeur, Anna Kaliina, top seed Aryna Sabalenka and Maria Sakkari to make her third career WTA final. Looking to notch her first win over Kontaveit, Alexandrova built a 6-4, 4-0 lead.

But history proved the win was never going to be easy. In their only previous meeting, Alexandrova served for the win and held two match points before losing 4-6, 6-2, 7-6(6) in Ostrava last year. This time, after getting a front row seat to another Kontaveit comeback, Alexandrova served for the match at 6-5 in the third set. She never saw a match point, and the resilience and confidence that Kontaveit had built up over her sizzling summer earned her the win in 2 hours and 22 minutes.

"I was just trying to stay in it as long as I could, and I never really gave up," Kontaveit said. "I was just trying to fight for every point as much as I could. If I would have lost 6-4, 6-2 or whatever, I knew I tried everything."

The grueling comeback win kept Kontaveit's WTA Finals chances alive. She would go on to dominate in Romania the next week and seal her spot in Guadalajara, where she made the final in her tournament debut. -- Courtney Nguyen

Sorribes Tormo wins marathon, showcases fighting spirit 

It doesn't get much more impactful than four hours of bruising clay-court tennis between two of the tour's polar opposites. In May, the Eternal City played host to what seemed like an eternal match as Sara Sorribes Tormo took on Camila Giorgi.

They started under the blue skies of a balmy Roman late afternoon, hadn't even completed the second set by the time night fell and finished under the floodlights after 3 hours and 51 minutes, with Sorribes Tormo winning 7-6(4), 6-7(7), 7-5. 

This season was one in which longueurs were markedly common, and Sorribes Tormo encapsulated that as she put together a career-best season that saw her rise 30 places to World No.36 and become a serious thorn in the side of the very best. Forty-two matches clocked in at three hours or more, and the Spaniard was involved in six of them.

In this clash, in which her astonishing retrieving skills were tested by a barrage of Giorgi bullets, Sorribes Tormo set a new standard of indefatigability. She saved three set points to win the first set; Giorgi needed seven to close out the second, before taking a 4-0 lead in the third. Ultimately, it was Sorribes Tormo who reeled off 16 of the last 18 points for victory.

Having exploited Giorgi's fading stamina with a sequence of exhausting slices in the third set, Sorribes Tormo looked as though she could run for another four hours afterward.

The match entered the record books as the sixth-longest of the Open Era, but by the end of the year had already been bumped down to eighth by Kristina Kucova's defeat of Ekaterine Gorgodze in Gdynia and Martina Trevisan's win over Marie Bouzkova in Indian Wells.

But as the ultimate Sorribes Tormo special, it encapsulated a player whose rise made for some of 2021's most memorable moments. -- Alex Macpherson