TENNIS player Monica Puig, who won the commonwealth’s first Olympic gold medal in Rio de Janeiro earlier this month, came crashing back down to earth, upstaged 6-4, 6-2 by China’s Zheng Saisai on Monday.

    “A lot of pressure, a lot of expectation but I can always continue to learn,” Olympic gold medalist Puig looked to the positives following her shock first-round loss at the U.S. Open.

    Zheng Saisai, ranked 61st at the U.S. Open, upset Puig, seeded 32nd.

    Zheng, 22, upset Agnieszka Radwanska at the Olympics. She’ll be seeking to reach the third round at a Grand Slam for the first time when she faces 59th-ranked Kateryna Bondarenko in the next round.

    “All credit to her, though. She played well. She complicated me just enough. But, you know, I’m still learning. I’m still growing. Trying to find the positives out of everything,” Puig said.

    She noted that Angelique Kerber, the player she beat in the gold-medal match, was able to come right back from a draining run in Rio de Janeiro to reach the final at Cincinnati. Kerber, in contrast, is 28 and an Australian Open champ and Wimbledon runner-up this year.

    “She’s been there,’’ Puig said. “She knows what it’s like. She knows she’s No. 2 in the world. She’s tested the waters out a little bit.

    “I’m brand new to this.’’

    And back when Kerber was brand new to being a major champion just a few months ago, she lost in the first round of her next Grand Slam. Garbine Muguruza, also 22, struggled as well following her French Open title.

    “A lot of people go through this,’’ Puig said. “It’s not just me.’’

    She upset Kerber, Muguruza and a third major champ, Petra Kvitova, on her stunning run to gold. Less than a week ago, Puig was in Puerto Rico, riding in a parade with other Olympians through streets packed with admirers — her victory a joyous respite from the island’s economic crisis.

    Then it was back to the grind of tennis. When she took the court Monday, with plenty of Puerto Rican fans cheering her on, she knew she wouldn’t be viewed as the player who has never made it past the fourth round at a major or the second round at the U.S. Open.

    And Puig will get back to working on how to start making some magical runs at the majors.

    “I need to keep racking up as much experience as I can,’’ Puig said. “You know what? This isn’t going to be the last of me. I know I’m going to keep working hard. The Olympics was something that happened because of all my hard work.’’

    Meanwhile, Novak Djokovic managed to emerge with a 6-3, 5-7, 6-2, 6-1 victory over Jerzy Janowicz of Poland at the U.S. Open on Monday.

    There were plenty of signs of trouble, starting with a visit from a trainer who massaged Djokovic’s bothersome arm after only five games.

    Asked about his health during an on-court interview, Djokovic deflected the question, saying, “I don’t think it’s necessary to talk about this now. I’m through. I’m taking it day by day.”

    (SD-Agencies)