Hard-serving Alex de Minaur has beaten local hope Reilly Opelka in the Atlanta Open to move within one match of claiming his second career ATP title.

The third seed won 7-6 (6-4) 6-7 (5-7) 6-3 and will now play either Briton Cameron Norrie or second-seeded American Taylor Fritz in Sunday’s final.

Despite the towering Opelka pounding 28 aces it was De Minaur who had the better serving on the day.

The Australian No.1 won 96 per cent of his first-service points and never gave Opelka a break point opportunity on a hot and humid day in Georgia’s state capital.

The turning point came in the third set when De Minaur finally broke Opelka’s serve, for the first time in the match, to go up 3-2.

The 20-year-old broke again on match point when the American sent a backhand into the net for his 38th unforced error.

“Reilly is an incredible competitor, a super tough guy to play and a great friend,” De Minaur said in a courtside interview.

“It’s a bit of a lottery out here. I just had to guess the right way (when returning) on a couple (of) big points and I was fortunate to get the win today.”

De Minaur became the youngest finalist in tournament history and will play in his fifth career ATP final on Sunday. If he wins, he’ll claim a second career-title after his Sydney International victory earlier this year.