Roger Federer overcame a slow start, then a late lapse, and needed five sets to win a topsy-turvy first-round match at the US Open against 19-year-old American Frances Tiafoe.
The No. 3-seeded Federer got broken in the first game and dropped the opening set, and then appeared to take control before letting a lead slip away.
Eventually, he edged the 70th-ranked Tiafoe 4-6, 6-2, 6-1, 1-6, 6-4 by breaking serve in the last game.
It was Federer's 79th career victory at the US Open, equaling Andre Agassi for second-most. Only Jimmy Connors has more, with 98.
Federer played under the closed roof at Arthur Ashe Stadium for the first time. He missed last year's tournament, when the retractable cover made its debut.