NEW YORK (AP)—Caroline Wozniacki won her first match as a Grand Slam tournament’s No. 1-seeded player, beating NCAA champion Chelsey Gullickson 6-1, 6-1 at the U.S. Open.

Because of long matches earlier, this one began at 11:52 p.m. Tuesday night and ended at 12:53 a.m. Wednesday.

The University of Georgia’s Gullickson, daughter of former major league pitcher Bill Gullickson, took the first two points and held a break point in the opening game. But Wozniacki erased that with an ace and eventually went ahead 3-0.

Gullickson, of Palm Beach Gardens, Fla., was making her Grand Slam debut two days after her 20th birthday. She isn’t ranked and got into the tournament with a wild card.

Wozniacki, who turned 20 in July, was the runner-up at last year’s U.S. Open.