World number eight Grigor Dimitrov finally managed to register his first win in the US Open, while Tomas Berdych and third seed Stanislas Wawrinka also advanced at Flushing Meadows on Wednesday.
Dimitrov, who made first round exits in his previous three attempts, defeated Ryan Harrison of America 6-2, 7-6 (4), 6-2 in just over two hours. The Bulgarian improved his head-to-head record to 2-0 over the American.
The seventh-seeded Bulgarian fired eight aces and racked up 37 winners against his American counterpart and was in complete control during his straight set victory over Harrison. Dimitrov will face Dudi Sela of Israel in the second round.
Czech Republic's Berdych also had it easy, comfortably seeing off former champion Lleyton Hewitt in straight sets at the Arthur Ashe Stadium. The Czech completely dominated the match and hit 43 winners to complete a 6-3, 6-4, 6-3 in two hours and 18 minutes.
"I feel pretty good," said Berdych. "It's a tough opponent, a big challenge. The conditions were extremely tough today.
"The heat, the wind, and facing Lleyton for the first round, it's not what you really want to have. But otherwise, when you are prepared and feel good, that's a perfect start."
In a second round match, Wawrinka battled past Thomaz Bellucci 6-3, 6-4, 3-6, 7-6 (1) at the Arthur Ashe Stadium in two hours and 36 minutes. Wawrinka made a strong start and won the first two sets, but the Brazilian clinched the third as the Swiss seemed to struggle.
Bellucci was looking to take the match into the fifth set, when he forced a fourth-set tiebreaker. The Australian Open champion, however, used his experience to go 3-0 ahead and fired back-to-back aces to take a 5-0 lead to eventually clinch the encounter on serve.
"I was really aggressive [In the first two sets] and coming to net as much as I could," Wawrinka said. "I was trying to keep the focus, but when you drop level against a player like Bellucci, it's tough. It was a streaky match."
South Africa's Kevin Anderson also battled past Pablo Cuevas to move into the second round by earning a hard-fought 6-3, 6-7 (3), 4-6, 6-2, 7-6 (1) victory. In a see-saw battle, Anderson managed to prevail over Cuevas in a fifth-set tiebreaker to register his 32nd win of the season.
In the second round, the lanky South African will lock horns with Poland's Jerzy Janowicz, who defeated Dusan Lajovic 6-3, 7-5, 5-7, 7-5. Meanwhile, Marin Cilic was forced to retire against Cyprus' Marcos Baghdatis.
In other matches, David Goffin of Germany defeated Niels Desein 6-1, 6-3, 6-3, Ernests Gulbis beat Frenchman Kenny De Schepper 7-6 (6), 3-6, 6-2, 4-6, 7-6 (2) and Portugal's Joao Sousa prevailed over Frank Dancevic 7-6 (6), 3-6, 6-2, 4-6, 7-6 (2).