(CNN) -- Top seed Caroline Wozniacki eased into the second round of the U.S. Open at Flushing Meadows, by beating qualifier Chelsey Gullickson in straight sets.
The Dane, who is seeded first in the absence of the injured Serena Williams, recorded a 6-1, 6-1 victory over American wild card Gullickson, though the match ended late in the night.
The 20-year-old told the tournament's official website that she was happy with the victory: "It's a long night. The matches before on the center court were so long. But, a win is a win, so it doesn't really matter what time I get on. As long as I win, I'm happy."
Last year's beaten finalist will now face Kai-Chen Chang of Chinese Taipei in the second round.
Elsewhere in the draw, Maria Sharapova fought back from one set down to defeat Australia's Jarmila Groth in three sets.
In temperatures approaching 100 degrees, the 2006 champion survived the early set-back to secure a 4-6, 6-3, 6-1 victory.
Serbia's Jelena Jankovic recovered from match point down to beat world number 96 Simona Halep in a contest which lasted over two hours.
Romania's Halep served for the match with the score at 5-4 in the third and final set, but Jankovic eventually prevailed, winning 6-4, 4-6,7-5.
Eighth seed Na Li of China was the highest-placed seed to be eliminated on Tuesday, succumbing to Russia's Kateryna Bondarenko.
Bondarenko, who reached the quarter-finals of this competition last year, lost the opening set before taking the match 2-6, 6-4, 6-2.
There were no such problems for seventh seed Vera Zvonareva, who took less than an hour to dispose of Slovakia's Zuzana Kucova. Zvonareva, who won the U.S. Open doubles title in 2006, breezed into the next round with a 6-2, 6-1 success.
There was reason for the American fans to cheers on day two also, with wild card Beatrice Capra celebrating a comfortable win over Croatia's Karolina Sprem. Competing at her first grand slam, 18-year-old Capra took the match 6-1, 6-3.