New world No.1⃣ @SabalenkaA is 🔒 in 😤 #USOpen
Aryna Sabalenka triumphed in her challenge against Kasatkina, winning 6-1, 6-3, and celebrated in her first match since securing the world No. 1 ranking.
Kasatkina was playing in her ninth consecutive US Open but had only reached the fourth round once, in 2017. This marks the second time this year she has made it to the second week of a Grand Slam, including the French Open.
She had three impressive victories against local favorite Alycia Parks, the former Australian Open champion, and world No. 97 Greet Minnen.
Sabalenka played her first match as the world No. 1, at least according to the live ranking, as her ascent to the top was guaranteed starting next Monday, ending Iga Swiatek's 74-week reign as the Polish dominator.
World No. 2 and world No. 13 maintained a 4-2 record in favor of Sabalenka, who won their last encounter just two weeks ago at the Cincinnati Open, 6-3, 6-3.
From the very first game, Sabalenka showed she arrived with the confidence of being the new world No. 1, securing three service breaks against Kasatkina and conceding only one game to take a 6-1 lead.
The Belarusian won 68% of the points played in the first set and capitalized on Kasatkina's weakness in her second serve, as she won only 13% of those points.
The second set maintained the tone of the first, with Sabalenka securing two more breaks, meaning Kasatkina couldn't win any of her first five service games.
World No. 14 defended her service for the first time in the fifth game of the second set, saving a break point. However, it was the only time she could hold her service, as Sabalenka finally take the set 6-3.
In the quarterfinals, she will face the young star Zheng Qinwen, who overcame Ons Jabeur 6-2, 6-4. The 20-year-old Chinese player reached the quarterfinals of a Grand Slam for the first time in her career and has no previous encounters with Sabalenka.
New world No.1⃣ @SabalenkaA is 🔒 in 😤 #USOpen