In one of the most anticipated first-round encounters, Andrey Rublev took down the 8th seed Stefanos Tsitsipas 6-4, 6-7, 7-6, 7-5 in three hours and 54 minutes for the tenth Grand Slam win. After advancing into the semi-final in Washington, Tsitsipas found himself in the top-5 but lost four straight matches, losing ground in Montreal and Cincinnati and suffering another early loss against the opponent who defeated Roger Federer in Cincinnati to gain a lot of confidence.
As was expected, two youngsters gave their best to control the rallies and the pace in the points, hitting many beautiful winners and maintaining the high level despite physical problems for both in the closing stages of the encounter, more vividly expressed on Tsitsipas' body.
There were 33 break chances in total and they managed to convert only eight, five of those coming from Rublev's racquet as he tamed his shots nicely to finish the clash with 51 winners and 47 unforced errors while the Greek counted to more than 80 mistakes.
The opening set was decided in the first game when Riblev moved in front, keeping the lead for a 6-4 advantage, staying neck and neck with Stefanos in set number two as well before the Greek claimed it 7-5 in the tie break to level the overall score and avoid a massive deficit.
Trading breaks in games six and seven in set number three, the rivals produced another tie break that Andrey grabbed 9-7 after fending off a set point at 6-7. They couldn't stay on the highest level in the fourth set, with 17 break points up for grabs and a 5-3 lead for the Russian who served for the triumph at 5-4.
Gathering the last energy in his body, Stefanos broke at love to level the score at 5-5 before losing the next two games to propel Andrey into the second round. The 24th seed Matteo Berrettini earned the first US Open victory, toppling Richard Gasquet 6-4, 6-3, 2-6, 6-2 in two hours and 43 minutes, firing 18 aces and fending off nine out of 11 break chances to mount the pressure on Gasquet who couldn't deal with it, suffering four breaks and ending his campaign in the first round.
Matteo stayed focused in his service games in the opener despite a couple of obstacles, scoring late break at 5-4 to gain the momentum, repelling two break chances at the beginning of the second set and stealing Richard's serve in the next game to forge the advantage that he carried home for a 6-3.
The Frenchman responded in set number three to extend the duel but that was all he could do, with Berrettini taking charge in the fourth set to move over the top and make a winning start. Mikhail Kukushkin took down the 10th seed and Wimbledon semi-finalist Roberto Bautista Agut 3-6, 6-1, 6-4, 3-6, 6-3 after three hours and 19 minutes, standing as the more aggressive player on the court and delivering seven breaks in comparison to five from Bautista Agut who made too many errors for the second consecutive first-round exit at the US Open.
Bautista Agut claimed the opener with a break at love in game four before losing ground in set number two when Kukushkin took charge with a double break, staying in control in set number three before coming back from a break down twice in the decider to cross the finish line first after rattling off four straight games for the place in round two.
Alexei Popyrin defeated Federico Delbonis 6-1, 7-5, 7-6, prevailing in the closing stages in sets two and three for the best possible debut in New York. The 22nd seed and a former champion Marin Cilic ousted Martin Klizan 6-3, 6-2, 7-6 in two hours and nine minutes, struggling to find the form in 2019 but playing well in this one to safely reach the second round.