Roger Federer improved to 18-0 in first-round matches at the U.S. Open and took one step toward a potential quarterfinal showdown against Novak Djokovic.

Dressed from head to toe in a plum-colored outfit, the 20-time major champion delivered 14 aces and never was in any trouble during a 6-2, 6-2, 6-4 victory over 117th-ranked Yoshihito Nishioka of Japan at Arthur Ashe Stadium on Tuesday night.

Federer saved the first eight break points he faced before finally faltering by pushing a forehand long on the ninth, losing serve for the only time while trying to close out the match at 5-2 in the third set. By then, the match was 1 hour, 45 minutes old — and it would last another seven minutes.

The No. 2-seeded Federer is seeking his sixth title at the U.S. Open, but first in a decade.

He would face 13-time major champion Djokovic if each wins three more matches.

Djokovic made a winning return to the U.S. Open, fighting through extreme heat that caused him to feel sick during his match to beat Marton Ducsovics in four sets.

Djokovic missed the U.S. Open last year because of an elbow injury and was playing his first match in Flushing Meadows since losing the 2016 final to Stan Wawrinka.

It was a tough one, until he dominated after players were allowed to leave the court for 10 minutes following the third and fourth sets. Once they returned, the No. 6 seed finished off a 6-3, 3-6, 6-4, 6-0 victory in 2 hours, 59 minutes.