AUCKLAND, New Zealand -- US Open champion Coco Gauff overcame hard-hitting Czech teenager Brenda Fruhvirtova 6-3, 6-0 on Thursday to extend her winning the start to the year and the defense of her title at the Auckland Tennis Classic.
The 16-year-old Fruhvirtova came out hitting harder than any player at the tournament so far: generating enormous power off both hands.
She troubled Gauff at first and broke the American's serve to love in the third game of the first set.
Gauff immediately broke back in a game of 14 points to level the set at 2-2. After saving a break point in her next service game, Gauff broke again to lead 4-2.
She served for the first set at 5-3 and had to save a break point before clinching the set in 40 minutes. Fruhvirtova tested Gauff with high top-spin, but Gauff came through and finished the set with an ace.
Gauff immediately broke Fruhvirtova in the first game of the second set as she began to find more depth in her returns. She also broke in third and fifth games and held her serve with confidence, highlighting her second service game with a 118 mph ace.
Gauff had to save two break points as she served for the match at 5-0 but managed to allay any threat with her sixth ace.
"I thought I played well," Gauff said. "She started really well and I was able to raise my level. I thought I served and I did better on my returns."
Fruhvirtova came into the match with a WTA ranking of 117.
"I thought she played a good match," Gauff said. "I've known her since she was 10 years old. We used to be in France, training at the same academy. Her and her sister (Brenda), we grew up playing or training beside each other and it's great to see her on tour. I'm sure she's going to go even further."
Gauff will play eighth-seeded Varvara Gracheva of France in the quarterfinals Friday. Gracheva beat Lulu Sun of Switzerland 6-3, 6-4.
Emma Raducanu's tournament ended when the 2021 US Open champion was beaten 6-7 (5), 7-6 (3), 6-1 by second-seeded Elina Svitolina in the final match of the second round.
But Raducanu will head to the Australian Open beginning Jan. 14 confident of her fitness in her return to tennis after a nine-month injury break.
She played two marathon matches in Auckland and came through both unscathed, though she played with heavy strapping on her right thigh Thursday. She took 2 hours, 27 minutes to beat qualifier Elena-Gabriela Ruse in her first match.
Her match with Svitolina was the most gripping of the tournament so far and lasted almost three hours.
Raducanu held a 5-2 lead in the first set but eventually had to take the set in a tiebreaker after 71 minutes. Svitolina led early in the second set, but Raducanu battled back to set up the tiebreak. She won the first two points against Svitolina's serve, but the formerly third-ranked Ukrainian then dominated and took the set in 67 minutes.
Svitolina took a 5-0 lead in the third set. Raducanu looked fatigued at times, but she still fought hard and stretched Svitolina when she served for the match at 5-1.
Seventh-seeded Petra Martic sent down six aces and converted four of nine break points on her way to a 6-2, 6-2 win over Yuan Yue of China. Martic will play American Emma Navarro in the quarterfinals.