Ben Shelton made history in more ways than one on Sunday.

The rising tennis star reached the quarterfinals of the US Open following an upset 6-4, 6-3, 4-6, 6-4 win over compatriot Tommy Paul in the round of 16.

Despite blowing a 4-1 lead in the third set, Shelton was eventually able to get the job done in the fourth. It was also a case of sweet revenge for Shelton who lost to Paul in four sets in the Australian Open quarterfinals earlier this year.

“I learned to be mentally tough,” Shelton said while reflecting on his defeat to Paul in Australia (via ATP Tour). “When I was playing in Australia after a long week I was looking at my box saying ‘My legs are dead, I am tired, I can't go anymore'.

“I realized how important it is to believe in myself. That I can go the full way emotionally and physically and now I have that belief here.”

With the win over Paul, Shelton notably became the youngest American male player at 20 years of age to reach the US Open quarterfinals since Andy Roddick achieved the feat back in 2002.

In the process, he also became the first NCAA singles champion to reach the US Open quarterfinals since John McEnroe in 1990.

“Being at home here in front of an American crowd, I have felt the love all week,” Shelton added. “I played another American today and we had a great battle. It is hard to believe I am playing on Arthur Ashe right now with the stands completely full.”

Speaking of Roddick, the 2003 US Open champion holds the all-time tournament record for the fastest serve at 152 mph back in 2004. Shelton's win over Aslan Karatsev saw him hit a 147-mph ace which was a tournament-best this year.

However, Shelton topped it against Paul after two 149-mph serves, one of which you can watch below:

In total, he struck 36 winners with 16 aces.

“I think straight adrenaline,” Shelton said of his 149-mph serves. “I think any other atmosphere I wouldn't be able to get it down and I think my arm might have come off. But it is feeling pretty good right now.”

Shelton is one of the brightest prospects on the ATP Tour and having previously reached a career-high of No. 35 in May, he is now up to No. 27 in the live rankings.

The Gainsville native will play one of fellow American Frances Tiafoe or Rinky Hijikata in the quarterfinals on Tuesday.