The world No.5 continued her perfect start to the year with a 7-5 6-2 win over 12th seed Belinda Bencic at Rod Laver Arena on Monday.

Bencic raced to a 4-2 lead but won just one of the next six games, dropping the opening set with a double-fault.

Sabalenka's superior serve was telling as she ran away with an eighth consecutive straight-sets victory of the year in one hour and 27 minutes.

"I'm super happy with the win today," Sabalenka said.

"(Bencic) is an unbelievable player, she played so good, and I'm super happy with the level today."

Sabalenka has spoken about trying to be more "boring" on the court - keeping her emotions in check - and did not drop her head when down a break early.

"It takes me a little while to understand that negative emotion is not going to help you on court," Sabalenka said.

"You just have to stay strong and believe, no matter what, and do everything you can to get back in the score and to win the match.

"I'm super happy with my mindset during the game today."

Sabalenka has made three grand slam semi-final appearances in the last two years but has never previously made the last eight at Melbourne Park.

The 24-year-old will meet Donna Vekic for a place in the semis after the unseeded Croatian secured a 6-2 1-6 6-3 win over Czech teenager Linda Fruhvirtova.

Former world No.1 Karolina Pliskova has also reached the quarter-finals after beating China's Zhang Shuai 6-0 6-4.

The Czech 30th seed blew through a near-flawless first set in just 21 minutes, pummelling 15 winners and half a dozen aces in the process.

Pliskova will meet Magda Linette in the last eight after the Polish world No.45 upset fourth seed Caroline Garcia 7-6 (7-3) 6-4.

Australian Associated Press