World No 1 Aryna Sabalenka said she still had room for improvement after a second dominant win in the Brisbane International on Thursday.
Sabalenka was pushed at times by 36-year-old Sorana Cirstea, but was never really troubled by the Romanian as she notched a 6-3, 6-3 win in 70 minutes.
The Belarusian will next play either 21-year-old Russian Diana Shnaider or Madison Keys, the American who beat Sabalenka in last year's Australian Open final.
Sabalenka said she aimed to get better as she targets a third Australian Open title in four years when the first Grand Slam of the year begins in Melbourne on 18 January.
"I think there is always room to improve, and I'm definitely not at my peak," Sabalenka said.
"Of course I prefer to win every match 6-0, 6-0, like everyone probably prefers, but at the end of the day you only get better when someone pushes you and you have to deal with moments under pressure."
Sabalenka said tournaments such as Brisbane, which features seven of the top 10 women, were perfect preparation for a Grand Slam.
"I think by bringing and having seven top players in the draw, it definitely helps to prepare better for the Australian Open," she said.
"I think it's important to have quality matches before heading to the big event, just so you're preparing yourself mentally for fights, for battles.
"And playing against top players is definitely a huge help heading into the Grand Slam tournament."
Another of the top names is former Wimbledon champion Elena Rybakina, who also reached the quarterfinals with a 6-3, 6-2 win over Spain's Paula Badosa.
World No 5 Rybakina took control at 3-3 in the first set, winning nine of the next 11 games to seal victory.
"It's always a tough battle against Paula, she has great shots, plays really fast and has a great serve," Kazakhstan's Rybakina said.
"I have a lot of things to work on for my next match but hopefully it's going to be better.