At the Australian Open, American Men Advance en Masse

Paul will face Roberto Bautista Agut, a Spanish veteran who is seeded 24th and is the only seeded player left in the bottom quarter of the draw.

The other players in that section are Shelton and Wolf, former collegiate standouts who will face each other on Monday. Shelton won the N.C.A.A. singles title last year for the University of Florida, where he was coached by his father Bryan Shelton, a former ATP Tour player. Wolf, 24, played for three years at Ohio State, where he was an All-American and the Big Ten player of the year in 2019.

Ben Shelton and Wolf have become friendly since Shelton turned pro last August. “I had seen him play in college tennis, but he was older than me, so we never competed against each other,” Shelton said of Wolf. “We’re good friends, like to joke around a lot, have a lot of locker room banter.”

Both are solidly built and powerful. Wolf has one of the most penetrating forehands in the game. Shelton, a left-hander, has one of the most intimidating serves, frequently surpassing 124 miles per hour. He has won 83 percent of his first-serve points in Melbourne and 64 percent of his second-serve points. Shelton was not broken on Saturday as he prevailed over Alexei Popyrin, the Australian who upset Fritz in the second round and again had a big home crowd ready to support him in John Cain Arena.

“They kind of set the tone when I walked out on the court, and I got booed,” said Shelton, laughing. “Similar to some away matches and college atmospheres that I have been at but definitely amplified today. The sound in there kind of just vibrates.”

But Shelton’s dominant play in his victory, 6-3, 7-6 (4), 6-4, often meant that the arena was unusually quiet. His shouts of “Come on!” reverberated through the space.

“Honestly, if this is the way he plays day in, day out, the guy is top 10 in six months,” Popyrin said.