World No.2 Aryna Sabalenka reached new heights in 2021. She won two titles, made her first two Slam semifinals and qualified for her first Akron WTA Finals in Guadalajara. The 23-year-old Belarusian leads the tour in match-wins with a 43-15 record.

We look back at the moments that defined Sabalenka's season:

Picking up right where she left off

Sabalenka finished the 2020 season on a high, reeling off her last nine matches to win back-to-back titles in Ostrava and Linz and finish in the Top 10 for the second consecutive season. She began her season in January at the Abu Dhabi WTA Women's Tennis Open, extended her winning streak to 15 matches and won her eighth career title. Sabalenka lost just one set over six matches, where she defeated Veronika Kudermetova 6-2, 6-2 in the final. 

Road to the WTA Finals: The best of Ashleigh Barty's 2021 season

Sabalenka's Abu Dhabi victory was a clear declaration of intent for the 2021 season and set her on the path toward the best season of her career. The Abu Dhabi title moved her to a career-high No.7 and she took that momentum into Melbourne. Kaia Kanepi ended her streak in the opening round of the Gippsland Trophy, but Sabalenka was relieved to go into the Australian Open with a clean slate.

"It was good to lose that match, not because of the pressure but because of kind of put me back in the reality," Sabalenka said. "I was trying to focus on the moment, but at that point I was thinking, like, nobody can beat me.  

"After the match I felt like, 'Well, thank you, Kaia,' that you bring me back into reality and now I can understand, 'OK, it's still the WTA Tour and everything can happen."

Sabalenka gives Serena Williams a scare 

Sabalenka took that mindset into the Australian Open, where she once again moved within a match of making her first major quarterfinal. Advancing to just her second Round of 16 at a Slam, Sabalenka played one of the most memorable matches of the season in a narrow 4-6, 6-2, 6-4 loss to Williams. Sabalenka stood toe to toe with the 23-time major champion, but rued the experience gap that she felt decided the match. 

"This is what I'm really disappointed with, and I would say that this is nothing to do with tennis," Sabalenka said. "This is more in my head, like, why would I miss easy shots? I just serve and then I think I made unforced errors for four points, like easy points for her. Why would I do this? I'm still young, but I thought that I have enough experience to handle all this pressure."

Sabalenka's improved consistency on display

Sabalenka had already proven she could produce unstoppable levels of tennis on her best days, but her inconsistency undermined her progress in the past. What set her 2021 season apart was her newfound consistency. Through her first eight events of the season, Sabalenka made the Round of 16 or better in all but one and made the quarterfinals or better in five.

In fact, it took the tour's biggest champions to keep the Sabalenka juggernaut in check. In the Middle East it was Garbiñe Muguruza - arguably the hottest player of the first quarter of the season - who ended Sabalenka's title hopes in Doha and Dubai. Then it was No.1 Ashleigh Barty, who stopped Sabalenka in the quarterfinals of Miami and final in Stuttgart. 

Sabalenka's clay-court breakthrough 

By the time the tour got to Madrid for the Mutua Madrid Open, the seeds of a burgeoning rivalry between Sabalenka and Barty were sown and the two would meet once again in the final. This time Sabalenka came out on top, edging the top seed 6-0, 3-6, 6-4 to win her first clay title and 10th title overall. 

Champions Corner: Inside Sabalenka's clay breakout in Madrid

Watch 'em all: Sabalenka's 40 winners vs. Kasatkina in Madrid

"I would say before I was too much thinking about the clay court, that this is surface not for me, that it's really tough to play on this surface, it's long rallies," Sabalenka said after winning Madrid. "I was really too much thinking about this.

"This year I kind of relaxed and kind of just play my game. I worked a lot on the movement, so I prepare myself really well for the clay court. My focus is just on my game, that I have to stay aggressive, that I have to move well on the clay court, make sure I can hit these shots really clean, heavy shots."

Disappointment in Paris

Sabalenka's Madrid win boosted her into the Top 5 for the first time in her career, and as the draw began to unfold at Roland Garros, and seeds bowed out early, Sabalenka emerged as a potential favorite for the title. 

But Sabalenka's quest to make her first major quarterfinal, let alone go further, ended in the third round to eventual finalist Anastasia Pavlyuchenkova. Sabalenka did well to come back and force a third set but played a wayward final set to lose 4-6, 6-4, 6-0 to end her clay season.

Photo by WTA/Jimmie48

Turning Point: Major breakthrough 

Sabalenka finally broke through her Round of 16 blockade at the Slams on the grass at Wimbledon. Coming off yet another quarterfinal run in Eastbourne, Sabalenka managed her opponent and her nerves to defeat Elena Rybakina 6-3, 4-6, 6-3 to make her first major quarterfinal. 

"I was struggling on the Grand Slams with all [the] emotions [I was] going through," Sabalenka said. "After every Slam I was so disappointed about myself that I can't handle this pressure. I actually thought that I will never make it to the second week. We worked a lot with my psychologist and with my coach."

While other players might achieve a milestone and experience an immediate letdown, Sabalenka followed up her Round of 16 win with a straight-sets victory over Ons Jabeur to make her first major semifinal. With a spot in a first Wimbledon final on the line, Sabalenka faced former No.1 Karolina Pliskova. The Czech played a pitch-perfect match to win 5-7, 6-4, 6-4, but Sabalenka would go on to prove her breakthrough was something to build on.

Breaking new ground in New York

After notching another WTA 1000 semifinal on the hardcourts of the National Bank Open in Montreal, Sabalenka went into the final Slam of the season at the US Open at a new career high of No.2. In New York, Sabalenka replicated her Wimbledon effort, advancing to back-to-back Slam semifinals, this time narrowly losing out to Canada's Leylah Fernandez, 7-6, 4-6, 6-4.