The 91st-ranked Tiafoe, the first wild-card recipient to win the title in its 26-year history, had consecutive aces on the final two points for a 6-1, 6-4 victory over Peter Gojowczyk of Germany.

At 20, Tiafoe is the youngest American to win a title since Andy Roddick won at age 19 in 2002 in Houston.

Tiafoe fell on his back in celebration and cried as he hugged his father.

"Now I'm in a position not only to help myself, but help fund my family," Tiafoe said. "It's an unbelievable place to be in, and it's bigger than tennis."

Tiafoe's parents moved from Sierra Leone to the United States looking for a better life. The elder Tiafoe ended up working as a maintenance worker at a Maryland tennis club, where the American-born Frances fell in love with the game. His twin brother, Franklin, wasn't interested in the sport.

"It's unbelievable," said Frances Sr., who now frequently travels the tour with his son. "I told them since they were little, 'Work hard and you can achieve your goal.' I told him, 'Whatever you put your mind to, you can do it.'"

Tiafoe, who should move up to approximately No. 61 in Monday's new rankings, was playing in his first career tour-level final at Delray Beach. He entered last week's New York Open, where he reached the quarterfinals, with nine career ATP tour-level match victories.

In this past two weeks, he has won seven tour matches. Among those recent victories is a second-round win over 10th-ranked Juan Martin del Potro last week.

Tiafoe was the last American to defeat Gojowczyk, which took place at the 2016 Winnetka Challenger in Illinois.

"I told you guys I was going to get him," said Tiafoe, laughing. "All the guys were texting me, `You have to take him out."

Gojowczyk had beaten his eight previous American opponents in ATP tour-level matches, including sixth-seeded John Isner, Reilly Opelka and Steve Johnson last week.

Overall, Gojowczyk had beaten the past 14 American players he faced in tour- and non-tour-level matches since that Winnetka loss to Tiafoe.

Gojowczyk was bothered by a left hamstring Sunday, which he said started during his semifinal against Johnson. The first time Gojowczyk called for the trainer to wrap his thigh was when he was about to serve with Tiafoe leading 5-0 in the first set.

"It was not my day, actually, today," Gojowczyk said. "But still it was a good week, and I reached my career-high (projected ranking of) 51 with this tournament.

"You want to compete, to go for the shots. And you want to play your best in the final."