Home favourite Naomi Osaka and Czech Republic's Barbora Krejcikova were among the top seeds who won in straight sets on Monday as normalcy returned to the Olympic Games following the shock defeat of top seed Ashleigh Barty of Australia on Sunday.No.2 Naomi Osaka, who became the favourite after Spain's Sara Sorribes Tormo sent Ashleigh home, looked solid in her 6-3, 6-2 victory over Viktorija Golubic of Switzerland.Naomi will meet the winner of the match between Czech Republic's Marketa Vondrousova and Romania's Mihaela Buzarnescu in the third round.After missing nearly two months without a match, there was a question mark over Naomi's ability to manage the pressure of winning gold in her home country. But, so far, she has looked invincible, not dropping a single set."Honestly, it's a bit interesting," she said of playing for the host nation. "The [Japanese] flag is always next to my name, but the scale here is much bigger. It's something I've been waiting for since Rio."Naomi played a superb first set, winning 24 of her 26 service points and converting her first set point with a backhand winner. She won 37 of 45 service points and faced only one break point.
"More than anything else, I'm just focused on playing tennis," Osaka had said after her first-round match, a 6-1, 6-4 win over China's Zheng Saisai. "The Olympics has been a dream of mine since I was a kid, so I feel like the break that I took was very (much) needed."Spain's No.7 Garbine Muguruza was an easy 6-3, 6-0 winner against Wang Qiang in 61 minutes. This was Garbine's 29th match-win of the season, and if the seeds hold, she'll have a third-round match against No.10 Petra Kvitova of the Czech Republic.No. 8 Barbora Krejcikova, the French Open singles and doubles champion this year, was nearly as dominant.She's now won 22 of her past 23 matches after defeating 18-year-old Canadian Leylah Fernandez 6-2, 6-4.Barbora needed 75 minutes to complete the match and next plays the winner of the match between No.9 Belinda Bencic of Switzerland and Japan's Misaki Doi.No.13 Anastasia Pavlyuchenkova of ROC defeated Anna-Lena Friedsam of Germany 6-1, 6-1 and will meet the winner of the match between Spain's Sara Sorribes Tormo and Fiona Ferro of France in the third round.