The top seed and the hometown favorite Naomi Osaka is through to the quarter-final at the Toray Pan Pacific Open, defeating world no. 181 Viktoriya Tomova 7-5, 6-3 in an hour and 30 minutes. The Japanese controlled the pace with 40 winners and 27 unforced errors, hitting 13 aces despite struggling to find the first serve and fending off five out of eight break chances to limit the damage in her games.
Tomova played well-composed and measured tennis, delivering 12 winners and only eight unforced errors to follow Osaka's pace in the bigger part of the encounter, playing against eight break chances and giving serve away five times to propel Naomi through.
Tomova made the best possible start, securing a double break for a 3-0 lead before Naomi pulled one break back, still trailing 4-2. Osaka broke back in the eighth game with a forehand winner, producing another one at love at 6-5 to take the opener following a double fault from the Bulgarian.
Just like in the opener, Viktoriya broke first in the second set before Naomi leveled the score at 2-2 with a forehand down the line winner, taking 12 of the last 13 points from 3-3 to seal the deal and move into the last eight.
The 9th seed Elise Mertens ousted Su-Wei Hsieh 6-3, 1-6, 6-2 in an hour and 53 minutes, suffering six breaks but seizing seven chances on the return to cross the finish line first and stay on the title course. The Belgian grabbed three straight breaks in the opener for a 6-3, losing ground completely in the second and allowing Hsieh to steal her serve four times in a row and build the momentum ahead of the decider.
Nonetheless, Elise found her shots when it mattered the most, breaking Hsien three times in a row to earn the victory and set the quarter-final meeting with Sloane Stephens or Camila Giorgi. The 5th seed Madison Keys had to work hard to topple Zarina Diyas 5-7, 6-0, 6-4 in two hours and five minutes, finding the path towards the finish line in the deciding set after a stellar performance in set number two.
Diyas had an early advantage in the opener, wasting it before landing another break in game 12 for a 7-5, hoping for more of the same in set number two. There, Madison was the only player on the court, earning a bagel and stealing the rival's serve twice in set three that propelled her over the top and into the quarters.
The 4th seed Angelique Kerber scored the first victory since Wimbledon, defeating a qualifier Nicole Gibbs 6-2, 6-4 in 80 minutes. Gibbs broke the German three times and that wasn't enough at least for a set, dropping almost 60% of the points behind the initial shot to get broken six times, forging a 4-1 advantage in set number two before Angelique took 20 of the last 24 points to complete a comeback and seal the deal in straight sets for a much-needed victory.