The 18-year-old from Perth recorded a first tour-level victory on Wednesday (AEDT), seeing off Poland's Magdalena Frech 6-4 4-6 6-1 in the opening round of the WTA 500 tournament in San Diego.
Wildcard Preston needed two hours four minutes to beat the world No.42 Frech, who made it to the Australian Open fourth round last month in Melbourne.
It is Preston's second career top-100 win and first against a top-50 player.
Last week, she reached the biggest singles final of her career at the WTA 125 tournament which moved her to a career-high ranking of 153.
Preston's second-round opponent is Ukrainian world No.34 Marta Kostyuk.
Anna Blinkova, meanwhile, engineered a remarkable comeback to defeat former No.1 Caroline Wozniacki 1-6 6-4 6-1. The Russian world No.51 lost eight of the first nine games of the match before turning the tables on Dane Wozniacki.
Blinkova battles 👊— wta (@WTA) Anna Blinkova defeats Wozniacki in a three set thriller 1-6, 6-4, 6-1. #SanDiegoOpen pic.twitter.com/UhVz1lrBAlFebruary 28, 2024
Croatia's Donna Vekic and Ukraine's Dayana Yastremska were among others moving into the second round.
Vekic, a tournament finalist in 2022, beat local wildcard and reigning US Open girls' singles champion Katherine Hui 7-5 6-2.
A first-time major semi-finalist at this year's Australian Open, Yastremska had to dig deep to outlast American Caroline Dolehide 6-4 5-7 6-1.
German veteran Tatjana Maria also advanced when eighth seed Leylah Fernandez retired with a left shoulder injury when down 0-4 in the second set. It marks the third consecutive year the 21-year-old Canadian, a US Open finalist in 2021, has failed to reach round two in San Diego.
Making her San Diego tournament debut, 36-year-old German No.1 Maria will now face Australian qualifier Daria Saville in the next round.
Maria beat former top-20 player Saville in their only previous meeting, which came at WTA 125 Barranquilla last year.
With AP
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