Frances Tiafoe next will face Rafael Nadal. (Aly Song / Reuters)

He guzzled pickle juice during changeovers, the better to keep from experiencing cramps in the Melbourne heat. And, after his latest hard-won victory, Frances Tiafoe ripped off his shirt, slapped his chest and roared like LeBron James.

He dropped to his knees and smacked the court with his hands as the magnitude of his latest Australian Open victory — coming on his birthday — sank in.

“It means the world. I worked my a — off, man. I told my parents 10 years ago I was going to be a pro and I was going to change their life and my life and now I’m in the quarters of a Slam at 21 years old,” he said, fighting back tears as he spoke of his parents, who moved to Maryland from Sierra Leone. “I can’t believe it, man.”

Believe it. He’ll face Rafael Nadal in a quarterfinal match at 7 p.m. Eastern on Monday. He got there by beating No. 20 seed Grigor Dimitrov, 7-5, 7-6 (8-6), 6-7 (7-1), 7-5, on Sunday. Nadal advanced with a 6-0, 6-1, 7-6 (7-4) victory over Tomas Berdych.

Tiafoe grew up in College Park, Md., taking up the sport at the Junior Tennis Champions Center with his twin brother, Franklin. The boys attended a program there because their father worked at the facility as the maintenance man.

“Look, I’m not saying you can’t make it if you grew up from a wealthy situation. I mean, a ton of people have. But obviously that gave me an incentive, a reason to give, a reason to work every day, understand why you do it,” he said Sunday. “Obviously it’s how bad do you really want to be successful, essentially. Like, what does that really mean to you? Why are you doing it?”

Ranked 39th, he had never advanced past the third round of a major until Sunday. And now, he’ll try to upend Nadal, who owns 17 major championships and is an opponent he has never faced.

“He’s going to run me like crazy,” Tiafoe said. “I’ve got to go to sleep now, matter of fact."

His parting words? “He better get ready.”

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