MIAMI, FL, USA – For so long her Achilles heel, Victoria Azarenka’s serve has become a real weapon of late.

It is an improvement that, allied with her exceptional returning, has helped the Belarusian re-establish herself as a contender at the game’s flagship events; in Indian Wells, she outplayed Serena Williams to collect her biggest title since being crowned Australian Open champion, and earlier this week in Miami she got the better of the next generation’s brightest star, Garbiñe Muguruza, over two enthralling sets.

Pivotal to her success against Muguruza was the serve. The statistics made pleasant reading for the Azarenka camp, nine aces and a solitary double fault helping her win 58 of 83 (69%) points on serve – WTA leader Serena Williams’ 2016 figure is 66.4%* – and restrict the Spaniard to two breaks.

“I think it was a high-quality match for both of us. It was a lot of good striking, a lot of winners, and both of us taking opportunities,” Azarenka said in her post-match press conference. “I think today I served really well, and I played to win in important moments. Momentum shifting, I think I was a little better today.”

The story was a similar one in the Indian Wells final, where her approach and execution withstood the sternest of examinations from one of the best returners in the history of the sport. Williams carved out 12 break points (three times as many as Azarenka) yet could convert only one.

“Well, I have to go for it. She’s not a type of player that if you going to play safe she’s going to give it to you or she’s going to miss,” the 26-year-old said afterwards. “You really have to go out there and take away, because there is nothing coming easy.

“My mentality was just to stay calm, do what I think is right, play aggressive, play my game, and figure it out from there. I just really try to stay in the moment. Whatever I can do, you know, whatever the score is, the next-best point what I can play.”

This unflappability bears stark contrast to previous seasons, when Azarenka’s serve often unraveled at the most inopportune of moments. Nowhere was this more apparent than during her encounter with Williams at last year’s Mutua Madrid Open. Leading 6-5, 40-0 in the final set, Azarenka fell to pieces, double faulting three times to precipitate a dramatic collapse that culminated in tie-break heartache.

Similar problems would haunt her for the rest of the campaign, which featured more false dawns than she would care to remember. Charged with finding a solution was coach Wim Fissette, who targeted cheap gains as crucial to improving his charge’s fortunes.

“I worked a lot on my serve to be able to create easier serving games and going for my shots, developing power speed, and now need to work a little bit more on accuracy,” Azarenka said after her Indian Wells victory over Samantha Stosur, a match in which she struck a healthy 10 aces.

In her Hawk-Eye tracked matches in 2015, Azarenka was averaging 96mph on her first serve and 84mph on the second. While her service speed has not risen noticeably in 2016 – she is averaging 100mph and 86mph on first and second serves, respectively – there has been a marked jump in the number of points won – 66% compared to 55% in 2015.

The knock-on effect has been a more confident player, better equipped to make that long-overdue charge up the rankings: “I think I’m a better player right now just the way I handle myself on the court. I improved a lot my serve and just stronger in the tougher moments. I feel happier on the court, so that’s very important, to be able to go out there and perform in a difficult fight.

“I think my game is developing with pretty big progress right now, and that’s what I’m most happy about, is being able to add a little bit more every time I play. That’s for me the main goal of this season, to keep improving.”

* Information accurate as of March 21, 2016