But he proved unbreakable in the clutch, digging out of trouble time and again before securing the title with an ace down the middle on the indoor hardcourt in Tennessee.
“I was overwhelmed with emotion there at the end of the match,” the 24-year-old from Louisiana said in a teary on-court interview.
Harrison, a former teenage prodigy who turned pro in 2007, had seen his form and ranking declined in recent years.
“I was fortunate to have a great start on the tour at a young age and after a lot of setbacks, and a few years of having my ranking drop a little bit, you get to a point where you’re not quite sure and you really don’t know if you’re ever going to achieve some of those things you always wanted to achieve, one of those being winning an ATP title,” he said.
“So for me to be where I am now, and where I was seven-or-eight months ago, and feeling like there was no light at the end of the tunnel, it’s surreal. I honestly can’t believe it.”
Harrison, who won every set he played the entire tournament without facing a tiebreak, will jump into the top 50 in the world rankings, after starting the tournament ranked 62nd.
The hard-hitting Basilashvili, meanwhile, could only lament failing to convert any of his 10 break point opportunities in the second set.
The world number 67 was seeking to become the first player from Georgia to win an ATP World Tour title.
But his prodigious power proved a double-edged sword in the final, as he made unforced errors in a baseline battle.
(Reporting by Andrew Both in Cary, North Carolina; Editing by Gene Cherry)