MELBOURNE, Australia (AP) — Frances Tiafoe rolled up his white shirt's right sleeve, flexed his biceps and slapped the muscle five times. Then he pounded his chest and yelled, "Yeah! Let's go! Let's go! Come on!"
Forgive the young American's exuberance. This was, after all, the biggest victory of his nascent career.
Down a set and 3-0 in the second, the 20-year-old Tiafoe came back to stun two-time Grand Slam finalist and No. 5 seed Kevin Anderson of South Africa 4-6, 6-4, 6-4, 7-5 on Wednesday in the Australian Open's second round.
"I went to a different place. I dug insanely deep," the 39th-ranked Tiafoe said. "It's all about competing. Guys are so good. It's just about how badly you want it. I want it real bad."
He was joined in the third round by another kid from the U.S. who'd never been that far at Melbourne Park, 21-year-old Taylor Fritz, who saved 12 of the 13 break points he faced while dispatching No. 30 seed Gael Monfils of France 6-3, 6-7 (8), 7-6 (6), 7-6 (5).
Next for Fritz is a matchup against Roger Federer, the two-time defending champion in Australia and owner of 20 Grand Slam titles.
"I grew up watching a lot of the guys I play today. I can't tell you how many times I watched Monfils' highlight reel on YouTube, just growing up. 'Fed,' obviously, my whole life growing up, he was always the best, winning everything," Fritz said. "So it's really cool being able to step on the court with him again."
A day after American men went 1-5, the country's contingent produced those two upsets and threw a couple of scares into other seeded players, too, but couldn't pull off the wins.
Mackenzie McDonald pushed No. 6 Marin Cilic before losing 7-5, 6-7 (9), 6-4, 6-4, and Denis Kudla went to a fifth set before bowing out 6-4, 7-5, 3-6, 6-7 (6), 6-4 against No. 18 Diego Schwartzman. Reilly Opelka, a 21-year-old who eliminated No. 9 John Isner in an all-U.S. first-round showdown, held a 67-2 ace advantage — and a 15-inch (38-centimeter) height advantage — against Thomas Fabbiano but lost to the Italian 6-7 (15), 6-2, 6-4, 3-6, 7-6 (5).
"This group (of Americans) really deserves the hype, I guess, because I think everyone's good," Fritz said.
Cilic was the 2014 U.S. Open champion and the runner-up at Melbourne Park to Federer last year. Against McDonald, an NCAA champion in singles and doubles at UCLA who is 23 years old and ranked 81st, Cilic delivered 25 aces, including on each of the last two points.
"It was a much tougher match than I expected," Cilic said. "I didn't know much about him."
For Tiafoe, it helped that Anderson's best attribute, his intimidating serve, slowed down along the way because of problems with his right arm. Anderson was repeatedly visited by a trainer during changeovers and he lost pace on his first serves as the match wore on.
Anderson was the runner-up at Wimbledon last year and at the U.S. Open in 2017 and had won all three previous matchups against Tiafoe.
But Tiafoe ended a six-match losing streak against top-10 opponents and is now into the third round at a major for the second time, equaling his best showing.
"These are the matches where they kind of define you and help you feel more and more comfortable to keep winning matches like that," Tiafoe said. "So, yeah, I'm definitely going to remember this one."
As for his postmatch flex, Tiafoe said: "I hope the crowd liked it."
Defeat Andreas Seppi of Italy next, and Tiafoe would make his debut in the second week of a Grand Slam.
He turns 21 on Sunday and said: "If I'm playing on that day and beat somebody, that's the best present I can get."
Federer, seeking a record seventh Australian Open title and third in a row, beat Dan Evans 7-6 (5), 7-6 (3), 6-3, and 2009 champion Rafael Nadal set up a third-round showdown against 19-year-old Australian Alex de Minaur with a straight-set victory of his own.
"I couldn't pull away early in the match," said Federer, who actually was two points from dropping the opening set.
The defending women's champion, Caroline Wozniacki, also advanced in straight sets, beating Johanna Larsson 6-1, 6-3, and will face Maria Sharapova next. Sharapova, whose five major titles include the 2008 Australian Open, had a 6-2, 6-1 win over Rebecca Peterson in Wednesday's last match.
Three-time major champion Angelique Kerber moved on with a 6-2, 6-3 victory over qualifier Beatriz Haddad Maia. No. 5 Sloane Stephens opened the day in Rod Laver Arena with a 6-3, 6-1 victory over her junior doubles partner Timea Babos.
Stephens, the 2017 U.S. Open champion, reached the third round of the Australian Open for the first time since 2014.
"I'm kind of conquering all the places where I've been terrible," Stephens said.
Four seeded women were sent home, including No. 24 Lesia Tsurenko, a 6-0, 6-2 loser against 17-year-old American Amanda Anisimova. No. 9 Kiki Bertens, No. 20 Anett Kontaveit and No. 29 Donna Vekic also exited. Vekic lost 6-4, 4-6, 6-1 to Kimberly Birrell, a 20-year-old Australian ranked 240th who got into the field as a wild card.
"It is so surreal," Birrell said. "That was just such a blur. I get to play again. It's crazy."
More AP Tennis: https://www.apnews.com/apf-Tennis and https://twitter.com/AP_Sports
This story has been corrected to show that Frances Tiafoe turns 21 on Sunday, not Monday.