Juan Martín del Potro, the seventh-ranked player in men’s tennis, made his last professional appearance in early July at Wimbledon in a semifinal match against Novak Djokovic that stretched nearly five hours.

It took del Potro, a 24-year-old Argentine, barely two-and-a-half hours to roll through his second- and third-round matches Thursday at the Citi Open at the William H. G. Fitzgerald Tennis Stadium in Rock Creek Park. Del Potro, the top seed in the tournament’s men’s draw, beat American Ryan Harrison 6-1, 7-5 in a second-round match that was delayed by Wednesday’s rainstorms. He cruised over Bernard Tomic later in the day in a third-round match that ended 6-3, 6-3.

The No. 16 seed, Marcos Baghdatis knocked out Kei Nishikori, the Association of Tennis Professionals’ 11th-ranked player, who took over the Citi Open’s No. 2 seed after Gael Monfils pulled out. Sam Querrey, the top-seeded American player, was bounced in the third round by Grigor Dimitrov 6-3, 6-2.

The Citi Open runs through Sunday.