The next stop on Ben Shelton's impressive debut run at the Australian Open will be the quarterfinals. (More Tennis News)

The 20-year-old NCAA champion from the University of Florida pulled out a 6-7 (5), 6-2, 6-7 (4), 7-6 (4), 6-2 victory over J.J. Wolf in an all-American matchup in John Cain Arena at Melbourne Park on Monday.

Shelton is playing in only his second Grand Slam tournament — and he is on his first trip outside of the United States in his life.?

He joins Sebastian Korda to give the U.S. at least two men in the quarterfinals in Australia for the first time since 2007.?

Yet another American could join them because Tommy Paul was in fourth-round action Monday, too, going up against No. 24 Roberto Bautista Agut of Spain.?

Also reaching the men's quarterfinals with a five-set win Monday was No. 5 seed Andrey Rublev.

The Russian kept coming back, kept coming back, kept coming back — from down 5-2 in the fifth set, then facing a pair of match points while trailing 6-5, then from 5-0 and 7-2 in the first-to-10 concluding tiebreaker — before finally putting away No. 9 Holger Rune 6-3, 3-6, 6-3, 4-6, 7-6 (11-9) at Rod Laver Arena.

Rublev won it when his backhand return slipped off the net cord and barely, just barely, made it over onto Rune's side of the court, impossible to reach. Rublev dropped to his back at the baseline and raised both arms as if to say, “Sorry!” — or perhaps “Sorry. Not sorry!” — while Rune also flung away his racket.?

In the quarterfinals, Rublev will meet either 21-time Grand Slam champion Novak Djokovic, the last man in the field with so many as one major trophy, or Australian Alex de Minaur, while Shelton's next opponent is going to be Paul or Bautista Agut.

In the women's quarterfinals, it will be Magda Linette — into the quarterfinals of a Slam for the first time at age 31 and in her 30th appearance at a major — against Karolina Pliskova, and Aryna Sabalenka against Donna Vekic.