World number one Aryna Sabalenka says tennis authorities "follow their interests" with regards to the tennis calendar and are not "focusing on protecting all of us".

Players have been raising concerns about the schedule in recent months, saying it is too long and intense.

Leading players on the women's tour are expected to play at least 20 mandatory events - four Grand Slams, 10 WTA 1000s and six 500s.

Belarusian Sabalenka said she would skip some events this year to protect her body.

"The season is definitely insane, and you see so many players getting injured," Sabalenka said after her 6-3 6-3 victory over Sorana Cirstea at the Brisbane International.

"The balls are quite heavy, so it's a lot of struggle for all of us."

Sabalenka and world number two Iga Swiatek were deducted ranking points for not playing enough WTA 500 events last season.

I'm skipping a couple of events in order to protect my body because I struggled a lot last season," Sabalenka, 27, added.

"Even though the results were really consistent, some of the tournaments I had been playing completely sick or I've been really exhausted from overplaying.

"This season we will try to manage it a little bit better, even though they are going to fine me by the end."

The WTA Tour has said player welfare will "always remain a top priority".

Four-time major singles winner Sabalenka says she is "definitely not at my peak" as she builds up to the Australian Open, where she is targeting a third title in four years.

"Of course I prefer to win every match 6-0 6-0, like everyone, but you only get better when someone pushes you," the four-time major singles winner said.

Sabalenka lost to Madison Keys in last year's Melbourne final.

Elena Rybakina continued her strong form from last year, claiming nine of the final 11 games in a 6-3 6-2 win over Spain's Paula Badosa.

Kazakh Rybakina, who won Wimbledon in 2022, beat Sabalenka at the season-ending WTA Finals and will be one of the title challengers in Melbourne.

She will face Czech Karolina Muchova for a place in the Brisbane semi-finals.

Meanwhile, China's Zheng Qinwen, the 2024 Australian Open runner-up, has withdrawn from this year's opening Grand Slam event as she continues to recover from elbow surgery.

"To play a Grand Slam requires players to maintain an extreme competitive condition," the Olympic gold medallist wrote on Instagram.

"I have not yet reached the best condition that I have set for myself."

In the men's event in Brisbane, Britain's Cameron Norrie fell 7-6 (7-4) 4-6 6-4 to American world number 58 Aleksandar Kovacevic in the second round.

In Auckland, former British number one Katie Boulter lost 7-5 6-4 to Ukraine's Elina Svitolina in a competitive second-round match.

Sonay Kartal was the sole British singles winner on Thursday, sweeping aside Germany's Ella Seidel 6-3 6-1.