One-third of John Isner's 15 career ATP titles have come at the Atlanta Open and the American will play for another Sunday against an up-and-coming countryman. 

Isner defeated Tayor Fritz 7-6 (7-4) 5-7 6-3 on Saturday to reach his first ATP Tour final this year after losing in the semis three times. 

One of those semi-final setbacks came last week in Los Cabos to Brandon Nakashima, who will be Isner's opponent Sunday. 

The 19-year-old Californian, ranked a career-best 115th, rallied to beat Finland's Emil Ruusuvuori 3-6 6-4 6-3 in the other semi. 

Nakashima defeated top seed Milos Raonic earlier this week and is riding high as he looks for his first ATP title. 

He is the first US teenager to reach the final in consecutive weeks since 18-year-old Andy Roddick won his first two ATP tournaments at Atlanta and Houston in the spring of 2001. 

Roddick's maiden title came in an earlier version of the Atlanta event. Since it was revived in 2010, Isner has won five of the 10 titles, with the first coming in 2013 about a week before Nakashima's 12th birthday.

"I didn’t know much about [Nakashima] prior to last week," Isner told the ATP's website. "But he kicked my ass last week, so we’ll see what I can do tomorrow.

"He’s 19 years old, that’s crazy. I was fishing on a boat when I was 19, here he is in the final of an ATP event.”