Two-time Grand Slam finalist Jasmine Paolini and teenage talent Mirra Andreeva on Sunday pulled out of this week's Adelaide International, citing a need to rest before the Australian Open.
With the first major of the season beginning on 12 January, Italian world No 4 Paolini withdrew after helping her country reach the quarterfinals of the mixed-team United Cup in Sydney.
"I need a bit more time to rest and recover after an intense week in Sydney," said last season's Roland Garros and Wimbledon runner-up.
She was joined on the no-show list by 16th-ranked Andreeva after she lost to world No 1 Aryna Sabalenka in the Brisbane International semifinals on Saturday.
Former Greek world No 3 Maria Sakkari, meanwhile, crashed out in qualifying to American Peyton Stearns, ranked 47.
The WTA-ATP tournament main draw gets underway on Monday, with world No 7 Jessica Pegula the women's top seed.