Taylor Fritz downs Alexsandar Vukic to claim the sixth title of his career in Atlanta

US number one Fritz dug deep to overpower Australia's Vukic, ranked 82nd in the world, in 2hr 16min, winning 7-5, 6-7 (5/7), 6-4.

Fritz looked to be heading for a straight sets victory after taking two match points on Vukic's serve while leading 6-5 in the second set.

But Vukic showed great character to claw his way back from the brink, eventually holding serve with an ace to force a tie-break.

The 27-year-old from Sydney then relied on his thunderous serve to grab the tie-break as Fritz was left ruing a golden chance to wrap up victory.

However the American regained his composure in the deciding set, claiming the decisive break in the seventh game to take a 4-3 lead before holding for 5-3.

Vukic then held comfortably but there was no way back as Fritz produced a dominant service game to seal victory.

A booming ace - his 16th of the tournament - brought up three match points at 40-0, and another powerful serve left Vukic flailing with a wild return to give the American the win.