Once Aryna Sabalenka understood what happened, she stood straight, applauded her opponent and started laughing. Moments ago, on the other end of the court, Dalila Jakupovic walked up to the baseline ready to serve, but instead of tossing the ball up, she sliced an underarm serve that caught Sabalenka off-guard, for her first ace in the final of the Mumbai Open WTA 125K Series at the CCI Courts.

Jakupovic could offer only a shrug along with a smile, as did the chair umpire, before Sabalenka too found humour in the shot. After all, the Belarussian had pushed Jakupovic to the brink. She had won the last 12 points in a row, leading 3-0 in the first set and already 0-40 up on Jakupovic’s serve.

“I didn’t understand what happened because I didn’t see her toss the ball,” Sabalenka says. “I’ve never faced an underarm serve before. But I made four errors after that serve.”

It was a last-ditch tactic that Jakupovic had in her arsenal against the brutal power-hitter Sabalenka, who had recently led Belarus to the Fed Cup final against the USA. On the day, however, the 19-year-old could not be subdued, as she ran away with a 6-2, 6-3 win in just over an hour.

This was Sabalenka’s first singles WTA-level title of her career, although she did come close to winning the Tianjin Open just last month, when she played five-time Grand Slam winner and idol Maria Sharapova in the final. Though the Belarussian came up short, she gave ample evidence of her lethal groundstrokes during the 5-7, 6-7 loss.

In Mumbai, she’s been raining down power-shots at her opponents all the way to the final. She started the summit clash in the same vein, breaking Jakupovic in her first service game. At 0-15, Sabalenka executed a strong backhand return winner. The next point, she hit an acute drive from the forehand to give her three break points. Jakupovic would concede the game with a double fault in the next point.

As it turned out, her aggression itself would stall her as the match went on. Serving in the first game of the second set, the world no 96 over-hit Jakupovic’s returns for a series of unforced errors to concede a break at love. “She’s got lots of power and aggression, but now she needs to learn how to control it,” says her coach Khalil Ibragimov. “There’s no point in trying to hit every ball as hard as you can.”

Standing at six-feet, the broad-shouldered teenager has also been working hard on her fitness to ensure her movement on court isn’t strenuous. “She hates doing it, but she does two hours of fitness work everyday,” Ibragimov adds. “The good thing is she understands that she has to do it.”

Despite the stern focus on her fitness, Sabalenka had Indian food on her mind while on her way to Mumbai. “I had been here two years ago, and loved the cheese garlic naan,” she says. “So when I got onto the flight to come here, all I could think of was cheese garlic naan.”

Since her last visit though, Sabalenka has broken into the top 100. She brings with her a fearsome intensity and demeanour on court. The win on Sunday will now push her ranking to the 60s, securing a first main draw appearance at a Grand Slam, the Australian Open, in January.