Two-time tournament champion and top seed Juan Martin del Potro needs just 70 minutes to oust Ryan Harrison at the Citi Open. (Katherine Frey/The Washington Post)

It had been nearly four weeks since Juan Martin del Potro last played a tennis match, losing a battle of brilliance to Novak Djokovic in the longest Wimbledon semifinal in history.

Thursday at Washington’s Citi Open, del Potro defeated two opponents in less than half the time of that memorable battle on grass.

The Argentine’s packed schedule was the result of Wednesday’s drenching rain, which halted play before four of the 16 second-round matches could be completed or started.

The tournament’s two-time champion and top seed sailed through the career-first challenge with ease, proving himself a cut above his two younger opponents in power, poise and shot-making.

Del Potro needed just 70 minutes to oust the misfiring Ryan Harrison, 6-1, 7-5, under muggy afternoon skies. He returned to the stadium court at William H.G. FitzGerald Tennis Center five hours later and was even more efficient against a more dangerous opponent, dismissing Bernard Tomic, 6-3, 6-3, in 69 minutes.

“I made a really good day,” said del Potro, 24, the 2009 U.S. Open champion. His reward is a quarterfinal meeting with the big-serving Kevin Anderson, who also had to defeat two opponents Thursday for the privilege. After ousting James Duckworth to start the afternoon, Anderson defeated American Mardy Fish, 7-6 (7-2), 6-1, in the evening.

While No. 2 seed Kei Nishikori and No. 3 seed Tommy Haas joined del Potro and Anderson in playing catch-up on the featured courts, Russia’s Olga Puchkova played hardball on a side court and was penalized harshly for it.

Puchkova was defaulted from the tournament and stripped of all prize money and points earned in the event for blasting a ball that hit a linesman on the knee, bruising him badly enough that he was taken from the court in a wheelchair.

Puchkova said in a statement that it was an accident and that she had apologized to the official.

“I’m sincerely sorry that I accidentally hit the line umpire in his knee,” Puchkova said through a Women’s Tennis Association spokesperson after leaving the grounds. “I wasn’t looking where the tennis ball would go.”

The incident occurred after Puchkova double-faulted while trailing 1-4 in the third set. Melanie Tabb, the WTA supervisor on site, said in an interview that she was convinced the contact was not intentional but explained it was a violation of the code of conduct nonetheless.

“I am sure it wasn’t intentional,” Tabb said. “She wasn’t looking where she was hitting the ball, from the report I received. I think she just hit the ball in frustration and unfortunately it hit the line umpire. It was a clear-cut situation, unfortunately, for a default. But I don’t think she ever meant to do it.”

Also facing double-duty, Nishikori eased past American Jack Sock, 7-5, 6-2, in the afternoon only to get toppled by Marcos Baghdatis, 6-1, 6-2, in their night match.

Haas followed del Potro on the stadium court and completed his second-round match against American qualifier Tim Smyczek in short order. But his evening clash with 13th seed Ivan Dodig was a struggle, with Haas prevailing 6-4, 4-6, 7-5 in a match that stretched past midnight.

“Obviously I’d be lying if I said it’s something players enjoy doing,” Haas said when asked about having to abandon play in the middle of a match and return the following day to complete it.

At 35, Haas has an assiduous program of pre- and post-match exercises and travels with a full-time physical therapist to keep him on task. After his match was halted Wednesday, it was 2 a.m. before he got to bed Thursday. He then returned to the grounds mid-day for the first of his two hurdles.

Del Potro took two weeks off to recover from his grueling Wimbledon semifinal then resumed training in Argentina, where it is winter. Returning to competition amid Washington’s thick humidity wasn’t easy, he explained.

But against Harrison, who sprayed forehands wildly and plowed too many backhands into the net, del Potro simply needed to remain steady to seize the upper hand. He won the first set in 22 minutes.

With his struggles continuing in the second set, Harrison spun around in disgust and screamed, “Oh my God!” then bashed his racket on the court.

Looking on from the stands was his coach Jay Berger, who suggested afterward that Harrison, 21, might have been trying to “show a little too much.”

Said Berger: “That’s not the tennis he has been playing. We’ve got to figure it out.”

At 6 feet 3, Tomic was a more formidable opponent. And del Potro wasn’t quite sure what to expect, having never played the 20-year-old. But though Tomic boasts a greater array of shots than Harrison, he lacked the focus Thursday to pull off many the drop shots and slices that mark his game.

And late in the second set, it was del Potro who looked the fresher, more engaged man.

It was a bad day for Americans Sam Querrey, Madison Keys and Melanie Oudin, who all were ushered out of the tournament.