A day after the American Mackenzie McDonald accounted for the men's top seed Rafael Nadal in straight sets, another American dispatched the second seed Casper Ruud.
Jenson Brooksby digested the disappointment of squandering three match points and then losing the third set to rally and achieve the biggest win of his fledgling career.
“Hopefully this is the first of many many good years here to come,” said the world number 39 after his 6-3, 7-5, 6-7, 6-2 victory.
By reaching the third round, Brooksby joins compatriots Ben Shelton, Tommy Paul and JJ Wolf, who also won Thursday, along with McDonald, Frances Tiafoe and Sebastian Korda, who all progressed on Wednesday.
Shelton and Wolf got past Nicolas Jarry and Diego Schwartzman respectively in straight sets while Paul came back to beat the 30th seed Alejandro Davidovich Fokina in five sets.
“A lot of Americans doing really well right now, and we're all pushing each other,” said Brooksby, who now will face Paul. “Just looking forward to the next one,” he added.
In the women's draw, the fifth seed Aryna Sabalenka breezed into the third round with a 6-3, 6-1 win over Shelby Rogers.
But there was a shock as the 21-year-old qualifier Katie Volynets defeated the ninth seed Veronika Kudermetova 6-4, 2-6, 6-2 to reach the third round of a Grand Slam tournament for the first time.
“I literally have the chills, because the fans here are just incredible,” said Volynets.
“I’ve never played in a stadium this packed and with that many people keeping the energy up for me. It was awesome.”
