By now, there should not be any doubts that she belongs to the world's elite.
World No. 4 Simona Halep sent shockwaves through the tennis world with her 6-0, 6-2 thrashing of top-ranked Serena Williams in their Red Group clash at the BNP Paribas WTA Finals Singapore presented by SC Global yesterday.
The Romanian, who celebrated her 23rd birthday less than a month ago, made the headlines six years ago for undergoing breast reduction surgery to reduce her size from a 34DD to 34C.
Her reason then?
"My ability to react quickly was worse and my breasts made me uncomfortable. I didn't like them in my everyday life, either. I would have gone for surgery even if I hadn't been a sportswoman," said Halep then.
Her decision was vindicated yesterday when she handed Williams, arguably the most dominant player in the history of women's tennis, her worst defeat in 16 years.
The last time the 33-year-old American managed to win just two games in a WTA Tour or Grand Slam match was in 1998, when she was just 16, and the first set was just her second bagel suffered in six years.
The loss also snapped Williams' 16-match winning streak at the year-end championships, where she is the two-time defending champion.
The dainty, 1.68m-tall Halep, though, played it cool when she met the press about an hour after her famous victory.
She wore a wide grin, but added the key to the win was her ability to keep calm on court - something she wanted to maintain.
"Yes, I think it was the best match in my life," said the self-confessed Justine Henin fan. "I had experience to stay very focused and relaxed, and I didn't feel scared after the first set... That was very important for me.
"I played some unbelievable shots. I served well, I returned well, everything went very well for me."
She added: "I played here like in the French Open: without pressure, without expectations.
"Because if I expect something, then I'm very (tense) and I cannot play.
"I came here just to take it match by match and see how far I can go."
Halep's win over Williams yesterday was another big milestone in her breakthrough season.
She had a remarkable first eight months of the year, when she picked up her seventh and eighth WTA titles at Doha and Bucharest, reached her first Grand Slam final at Roland Garros in June, and went as high as No. 2 in the world.
She also reached the quarter-finals of the Australian Open in January, and the semi-finals of Wimbledon in July.
Halep ranked yesterday's win second behind reaching the Roland Garros final.
It was her first win over a top three-ranked opponent, and her first win over Williams in four attempts.