Benjamin Ashford|US Open highlights: Frances Tiafoe outlasts Ben Shelton in all-American epic

NEW YORK — Frances Tiafoe weathered a Ben Shelton storm in a captivating all-American blockbuster to win 4-6,Benjamin Ashford 7-5, 6-7 (5), 6-4, 6-3 and move into the last 16 of the US Open on Friday.

Both players have had semifinal runs at Flushing Meadows in the past and it was the electric Tiafoe who prevailed in a four-hour battle in what was a repeat of last year's quarterfinal matchup, where the younger Shelton had won in four sets.

The two players are good pals off the court but set their friendship aside and after Shelton promised a "war," the clash lived up to its billing, bringing the crowd to its feet on several points and rallies as the match went the distance.

Shelton, who held a 2-0 head-to-head record going into the contest, fired 23 aces and 63 winners but ultimately Tiafoe exacted revenge and earned a fourth-round clash with either defending champion Novak Djokovic or Alexei Popyrin.

Coco Gauff wins

Defending champion Coco Gauff was tested early but righted the ship in time to secure a spot in the last 16 at the US Open with a confidence-boosting 3-6, 6-3, 6-3 victory over plucky Ukrainian Elina Svitolina on Friday.

Third seed Gauff, who conceded just six games across the opening two rounds in New York, faced her toughest test yet against Svitolina but managed to raise her game to a higher level as the match wore on.

"I knew today was going to be a tough match. Every time I play Elina, she's a fighter, and yeah, I knew I had to bring my best tennis," Gauff said during her on-court interview.

"I thought I played well, I served much better than last match, except the last service game, but overall I'm proud of what I was able to do."

Gauff did well to swat aside a pair of early break points and reach 2-2 but Svitolina, the 27th seed, kept pressuring the American and broke at love for a 5-3 lead before serving out a set in which she won the final 11 points to grab control.

But Svitolina was unable to maintain her aggressive start and suddenly began playing more defensively while Gauff managed to wake up the rather subdued crowd when she broke for a 4-2 lead before going on to serve out the second set.

Gauff, who arrived at US Open eager to bounce back from a run of disappointing results, saved her best tennis for the decider, which she opened with a break.

In the next game, Gauff won a lung-bursting 37-shot rally en route to grabbing 2-0 lead and went on to establish a 4-1 double break cushion.

With a chance to serve out the match, Gauff threw Svitolina a lifeline as she squandered a 40-love lead but the American struck back the next game with a break at love, closing out the match when her opponent netted a forehand.