MELBOURNE, Australia -- Tommy Paul received a lot less attention than his younger, less-experienced opponent, Ben Shelton, heading into their all-American quarterfinal at the Australian Open.

Perhaps that was a product of the fascination with the out-of-nowhere Shelton: Just 20, and less than a year after winning an NCAA title for the University of Florida, he was traveling outside of the United States for the first time and participating in his second Grand Slam tournament.

So the loud shouts of support heard most often at Rod Laver Arena on Wednesday under the sun that carried the temperature to 87 degrees Fahrenheit were for one of the pair: "Let's go, Benny! Let's go!'' or "Benny, Benny, Benny! Oi, Oi, Oi!'' or "Go, Gators!''

"He had a pretty good trip,'' Paul noted.

Paul's story is a pretty good one, too, and it is the one that will keep going at Melbourne Park: The 25-year-old from New Jersey was a star in the juniors and now is making good on that promise in the pros, using a 7-6 (6), 6-3, 5-7, 6-4 victory over Shelton to reach his first Grand Slam semifinal in his 14th appearance at a major.

As a bonus, Paul's mother was in the Rod Laver Arena stands for the biggest victory of his career. He said Mom booked a flight after he won his fourth-round match, then he went straight from work to the airport to make the long journey from the U.S. to Australia.

"Making it to the second weekend of a Slam, that's everyone's dream when they start to play tennis,'' the 35th-ranked Paul said, "so I can't believe I'm here right now.''

His path to this point went like this: He broke through as a teenager, taking the 2015 junior title at the French Open and getting to the final at Flushing Meadows that year, too. Since turning professional, he has claimed one tour-level trophy, at Stockholm in 2021, and, until this week, had made it as far as the fourth round at just one Grand Slam tournament -- at Wimbledon a year ago.

Now Paul is the first man from his country to make it to the final four at Melbourne Park since Andy Roddick in 2009. Roddick was also the last man from the U.S. to win a Grand Slam singles championship, at the US Open 20 years ago.

Paul's next opponent will be 21-time Grand Slam singles champion Novak Djokovic or Andrey Rublev. The other men's semifinal Friday is Stefanos Tsitsipas against Karen Khachanov.

Based purely on ranking, Paul offered a much sterner test than anyone Shelton had faced in Australia: His prior opponents were ranked 67th, 96th, 113th and 154th.

Paul, meanwhile, took out two seeds: No. 24 Roberto Bautista Agut and No. 30 Alejandro Davidovich Fokina.

This matchup was the first singles quarterfinal between two American men at any Grand Slam event since 2007, when Roddick beat Mardy Fish in Melbourne, and Paul generally was content to block back those big lefty serves that kept coming from Shelton, then do what he could to get the better of baseline back-and-forths.

Paul was more steady than spectacular, limiting his miscues with compact swings off both wings.

Leading into the match, Shelton called Paul a "good friend'' and credited him with being "one of the American guys who's kind of almost taken me under their wing, kind of helped me navigate some of the early stages of a professional career.''

They shared a light moment when Paul's coach, Brad Stine, told him to look for a serve down the "T'' on the ad side of the court. Shelton noticed the exchange and kicked his serve wide, leaving Paul out of position and with no chance at reaching the ace. Both players smiled.

Already up two sets, Paul broke to lead 4-3 in the third, then was serving at 30-love. But he went through a bit of a lapse. He missed a forehand, was forced into an errant forehand, double-faulted and missed a forehand to get broken for the first time in the match.

Shelton broke again to steal that set when Paul sailed a backhand long. Shelton -- the far more demonstrative of the two players -- yelled, "Yeah!'' as he raised his left fist, then pointed to his ear with his right index finger, as if telling the crowd, "Let me hear you!''

Maybe Shelton relaxed a bit there, because he started the fourth set slowly, double-faulting twice in a row then missing a backhand to gift wrap a break for Paul, who quickly went ahead 2-0.

Soon enough, it was Paul letting out a scream of delight -- "Let's go!'' -- after the last point, then meeting Shelton at the net for a warm hug.

The Associated Press contributed to this report.