As hard as it may be to top the high that Elena Rybakina was on following her thrilling victory on Tuesday, it may be even more difficult to understand the low she felt only moments later.

The 20-year-old Kazakh and No. 14 seed at the Qatar Total Open in Doha fended off match point to survive unseeded Belgian Alison Van Uytvanck 5-7, 6-2, 7-6 (8) and advance to the Round of 16 at the tournament.

The victory was the 21st of the season for Rybakina, building on the winningest start by a player on the WTA Tour in a dozen years, and booked her a spot in the quarters with top-seeded Ashleigh Barty of Australia.

But shortly after the win, Rybakina withdrew from the tournament because of an abductor strain.

"I'm really sorry but I have to withdraw from Doha," Rybakina said in a statement. "I have a small strain in my leg and I don't want to risk it getting worst. I will definitely be back next year, thank you for your support!"

Instead, Barty will face the winner of Spain's Garbine Muguruza and Ukraine's Dayana Yastremska. The 11th-seeded Muguruza breezed past Australian Ajla Tomljanovic 6-1, 6-2 while Yastremska stunned sixth-seeded Sofia Kenin of the U.S. 6-3, 7-6 (4).

"It's really frustrating," Kenin, the 21-year-old Australian Open winner and highest seed to lose Tuesday, told reporters after losing to the 19-year-old Yastremska. "Obviously coming off of Melbourne, where I felt I was playing the best tennis of my life, coming down to playing, not the worst tennis, but not playing the tennis I want to be playing."

For her part, Barty made quick work of Germany's Laura Siegemund 6-3, 6-2.

Among Tuesday's other winners were third-seeded Karolina Pliskova of the Czech Republic -- a 6-3, 6-0 win over unseeded American Bernarda Pera -- and fourth-seeded Belinda Bencic of Switzerland. She beat unseeded Russian Veronika Kudermetova 6-4, 4-6, 7-6 (4).

Mexican Open

Mexico's Renata Zarazua, ranked 270th in the world, stunned top-seeded Sloane Stephens of the United States 6-4, 6-2 in the first round at Acapulco, Mexico.

The result continued Stephens' miserable start to 2020. Stephens has lost in the first round in all four events she has played, including a defeat to another player outside the top 200, Arina Rodionova, in Adelaide, Australia.

Venus Williams also was stunned in the opening round, squandering seven match points -- all in the same game -- while falling 4-6, 7-6 (4), 6-2 to 19-year-old Slovenian qualifier Kaja Juvan. Williams could have put the match away at 4-5 in the second set, but Juvan's escape act turned the match around.

Sixth-seeded Lin Zhu of China beat Ukraine's Katarina Zavatska 7-6 (2), 6-2, but fourth-seeded Lauren Davis lost an all-United States battle with Christina McHale, 6-2, 1-6, 6-4.