It was just a matter of time before Maria Sakkari would break through. The 26-year-old spent her 2021 campaign rewriting the history books of Greek tennis after becoming the first woman from her country to reach a major semifinal, make a Top 10 debut and qualify for the Akron WTA Finals Guadalajara. 

Here's how the best season of Sakkari's career unfolded: 

Melbourne hard quarantine derails season start

After finishing her 2020 season with a semifinal run in Ostrava, Sakkari picked up right where she left off. Tallying a trio of wins over Coco Gauff, Sofia Kenin and Garbiñe Muguruza, Sakkari opened her season by making the Abu Dhabi semifinal, where she lost to eventual champion Aryna Sabalenka. All signs were pointing to a positive start and hopeful chances as Team Sakkari headed to Australia. 

Coaching Dossier: Get to know Top Hill

But Sakkari and coach Tom Hill landed in Melbourne only to learn that they would have to spend 14 days in hard quarantine after a passenger on their flight tested positive for COVID-19. Sakkari did well to come out of it to make the semifinals of the Grampians Trophy, but there was no denying the effect of her two weeks away from the courts. She bowed out in the first round of the Australian Open to Kristina Mladenovic, 6-2, 0-6, 6-3.

Road to WTA Finals, singles

Road to WTA Finals, doubles

"I think after the two weeks in Australia, stuck in the room, I lost a little bit of my identity, which is being aggressive but also making a lot of balls and playing physical matches," Sakkari told WTA Insider in March. "Even though I had a couple of good wins after that, I wasn't feeling it."

Through the Middle East swing, Sakkari still found herself searching for her game. A good run to the Doha quarterfinals seemed to indicate things were going in the right direction, but it was followed up with a first-round loss in Dubai. In retrospect, the two losses - to Muguruza in Doha and Barbora Krejcikova in Dubai - were nothing to worry about given the quality of opponents. But Sakkari was left reeling.

Maria Sakkari saved six match points against Jessica Pegula in the fourth round of Miami, five at 4-5 in the decider and one in the tiebreak, to win 6-4, 2-6, 7-6(6). Sakkari struck clean winners on five of those.

Getty Images

Dubai reset results in Miami success

After her 8-5 start to the season, Sakkari stayed in Dubai to work and diagnose the issues in her game.

"Tom was like, 'Look, I know you hate watching yourself playing, but we have to do it,'" Sakkari said. "So we sat down and we watched a few matches from Ostrava, because I think I was playing good tennis back then, as well. A few matches from Abu Dhabi. Just looked at what I was doing differently than the matches that I lost after the Australian quarantine."

Read: How Sakkari rediscovered her identity ahead of Miami

The reset worked. In her next tournament, at the Miami Open, Sakkari forged a path to her first WTA 1000 semifinal since 2019 and third overall. Her run was highlighted by a memorable comeback against Jessica Pegula in the Round of 16, wherein she saved six match points to win 6-4, 2-6. 7-6(6).

She followed that up with a dominant win over Naomi Osaka in the quarterfinals, 6-0, 6-4, before coming up short in one of the most compelling matches of the season, where against Bianca Andreescu she lost 7-6(7), 3-6, 7-6(4).

Maria Sakkari Roland Garros

WTA/Jimmie48

Breakthrough: First Slam semifinal at Roland Garros ends in heartbreak

Sakkari posted back-to-back Round of 16 appearances to start her clay season in Stuttgart (l. Kvitova) and Madrid (l. Muchova) and a second-round showing in Rome (l. Gauff). All three losses came in three sets.

Sakkari's Slam breakthrough finally came at Roland Garros. Before Paris, Sakkari's best result at the majors came with two Round of 16 appearances in 2020 at the Australian Open and US Open. But results aside, clay remains Sakkari's favorite surface, and she proved her prowess by defeating Elise Mertens before knocking off last year's finalist and champion, Sofia Kenin and Iga Swiatek, without losing a set to advance to her first major semifinal.

Read: Sakkari stuns defending champion Swiatek to seal semifinal spot

"I thought about it a lot of times that maybe that [Top 20] was my ceiling and I could not get any higher in the rankings, playing better in tournaments," Sakkari said in Paris. "But this year I proved myself that I'm actually playing really good. I beat a lot of very good players."

Facing eventual champion Barbora Krejcikova for a spot in her first major final, Sakkari held a match point at 5-3 in the third set before the Czech mounted a comeback to win, 7-5, 4-6, 9-7. It was a crushing loss for the 26-year-old. 

"I have to be deadly honest: I got stressed, starting thinking that I'm a point away from being in the final," Sakkari said after the match. "I guess it's a rookie mistake. 

"Good thing is that if I give myself a chance again to be in that position, then I know that I don't have to do it again." 

Maria Sakkari US Open USTA

Darren Carroll/USTA

Securing second Slam semifinal in New York 

Sakkari would go 3-3 at WTA tournaments after Roland Garros. But as she proved in Paris, she had come to learn how to summon her best tennis at the biggest tournaments, and she channeled all her learnings into the US Open to make a second consecutive Slam semifinal. In New York, Sakkari scored wins over Petra Kvitova, avenged her Miami loss with a three-set victory over Andreescu, and put together a dominating win over Wimbledon finalist Karolina Pliskova in the quarterfinals.

"I think I had one of the toughest draws," Sakkari said. "Kostyuk, Siniakova, Kvitova, Andreescu, Pliskova, all these players are players I don't want to play in the first rounds. Going deep, you won't have it easy. I had to play really well to be here. That gives me a lot of confidence because I beat some very, very good players to reach the semifinals this time."

Sakkari fell short against surprise champion Emma Raducanu, but her successful fortnight boosted her to No.12 in the rankings and on the verge of a Top 10 debut. 

Making Greek History: Ostrava Final triggers Top 10 debut and WTA Finals qualification

Motivation was not a factor for Sakkari after the US Open. With an eye toward making history as the first Greek woman to crack the WTA Top 10 and qualify for the WTA Finals, Sakkari followed up her US Open semifinal with a run to the Ostrava final. En route, Sakkari defeated Jelena Ostapenko and upended Swiatek for a second time this season, before losing to a red-hot Anett Kontaveit in the final. 

"It would sound crazy and stupid if I said that I'm not motivated because I'm trying to achieve one of the biggest goals of my career for the first time, which is the Finals," Sakkari said. "I'm more motivated than I was the first week of the year." 

Sakkari's Ostrava run was enough to rewrite the history books the following Monday and book her spot in Guadalajara, where she will compete at the WTA Finals for the first time in her career. En route to her WTA Finals debut, Sakkari posted a 36-18 record during the regular season and posted a 7-3 record vs. Top 10 opponents on the WTA Tour. Before 2021, Sakkari was 10-13 against Top 10 opposition.