TOKYO, Japan - Garbiñe Muguruza overcame an initial resistance from Monica Puig to begin her reign as World No.1 with victory at the Toray Pan Pacific Open, beating the Puerto Rican 6-4, 6-0 to make the quarterfinals.
The Spaniard, who was confirmed as the 24th player to reach top spot in the world earlier this month, came up against stiff competition in the opening set, trading breaks of serve before ultimately emerging victorious in 74 minutes.
"I'm very happy because it's my first match as No.1," Muguruza said. "Last time I played her, it didn't go my way at all. This time, I found a better way to play...so that's something that I improved. It's always good to be in Tokyo, playing the first tournament in Asia."
Puig had won the only previous meeting of the players with the loss of just two games, at the 2016 Rio Olympics during her magical run to the gold medal, and maintained momentum early on.
Both players saved two break points in their opening service games, Puig losing her serve on the third while Muguruza held hers.
"When I played her [in Rio], she played very well," Muguruza assessed. "That day, it was credit to her. Today, I think I improved a lot. I'm more confident and knew I had to go out there and be very aggressive. I always try to play my game, so maybe the confidence, playing better, and making the right decisions helped me today."
"It was a tight match though -- especially the first set and even in the second set, all the points were tough. I kind of learned a little bit what worked in the first set. She made a few more mistakes, I made a few more good shots, and it went my way."
Puig broke back to level at 2-2 and displayed impressive resolve, making Muguruza work hard for the set and serving just one double fault. The Spaniard broke again for 3-2 and took the opener on her second set point.
The second set was a more one-sided affair, as Muguruza found her groove after breaking in the opening game. A stretch of 12 points won in succession formed part of another break as the Spaniard raced into a 4-0 lead.
Puig rescued four break points in game five of the second set but was not able to stop a rampant Muguruza, who eventually broke once again to leave herself a service game to see out, which she did to take her place in the last eight.
"Nothing has changed -- I think on paper it's different," said the Spaniard about playing as World No.1 "You can feel like you're the top seed, but overall, I'm not thinking, 'Oh, I'm No.1, I should win easily.' Every match is going to be tougher now."
Winning in 74 minutes, she will face either home wildcard Kurumi Nara or Caroline Garcia next as she takes part in the quarterfinals at this event for the fourth year in succession. Her best showing remains the semifinal she lost to Caroline Wozniacki in 2014.