Rybakina confirmed she will replace Aryna Sabalenka at the top of the world rankings on Monday with her US Open quarter-final victory over China's Zheng Qinwen.
Despite losing a set for the first time in the tournament, Rybakina fought back and saved a break point in the deciding set to complete a 3-6 6-1 6-4 win.
She is the first Kazakhstani man or woman to reach the top of the singles standings.
Rybakina has been in hot pursuit of Sabalenka this season and arrived in New York as one of three women who threatened the Belarusian's position, alongside Americans Jessica Pegula and Coco Gauff.
However, the other three contenders each needed to win the title and hope Rybakina exited before the semi-finals to capture the number one spot.
Sabalenka's consecutive 99-week reign as world number one stretches back to 21 October 2024 and stands as the sixth-longest streak in WTA history.
The top two players could yet meet in the US Open final - just as they did at this year's Australian Open, where Rybakina prevailed in three sets.
For Rybakina, the trophy is more important than her new ranking.
"It's just a number right now. My goal is to win the tournaments which I play," the 27-year-old sad.
"It's an amazing achievement, but you know how quickly everything can change in tennis ranking-wise. "
Rybakina will face either Coco Gauff or Mirra Andreeva in Thursday's semi-finals, while Sabalenka takes on Jessica Pegula.
After losing to Sabalenka in the quarter-finals of the Wuhan Open last October, Rybakina clinched the Ningbo Open title one week later before taking her revenge by beating Sabalenka to win the season-ending WTA Finals.
She carried that momentum into 2026, getting the better of Sabalenka again but this time in a major final. She beat her fellow big-server in three competitive sets to win the Australian Open - her second Slam title almost four years after her first at Wimbledon.
Since then, Sabalenka has come out on top in their Indian Wells final and Miami Open semi-final, but Rybakina took the Stuttgart title on clay as Sabalenka's form fluctuated.
After disappointing early exits at the French Open and Wimbledon, she reached the final in Toronto, losing in straight sets to Iga Swiatek.
Rybakina's bid to replace Sabalenka suffered another setback when she was forced to retire injured from her Cincinnati Open quarter-final against Swiatek last month.
Rybakina later revealed that the left ankle problem, which hindered her movement and prevented her pushing off properly when serving, had been "bothering me for a long period of time" but was something she felt she had "under control".
Speaking before the US Open, Rybakina admitted her preparation "wasn't great" as she was unable to train for much of the week leading into the tournament.
However, that has not stopped her from achieving the first of her two major goals in New York.
Despite managing her ankle injury in the lead-up to the US Open, Rybakina has backed up a 78-match 2025 season by playing 60 times so far this year.
She has won 47 of those matches, a tally bettered only by American world number three Pegula (50) on the WTA Tour.
Only Pegula can match her tally of 34 wins on hard courts this season.
But Rybakina has also won the majority of her matches against the tour's other leading players, winning 13 of her 20 meetings with fellow top-20 players.
Undoubtedly Rybakina's biggest weapon is her powerful serve.
She has recorded the most aces on the WTA Tour this year, with her total standing at 394 in 2026.
Rybakina's serve was at its devastating best against Naomi Osaka in the fourth round - she won 87% of her first-serve points and fired in seven aces among her 29 winners, but limited her unforced errors to 17.
Speaking after the match, Osaka said: "The immediate thought that I had in my head when she hit the ace, I was, like, 'well, I can't really do anything about it'. "
"Maybe I could have covered it, but she has a great serve, so she probably would have hit the other way. "
