Aussie duo and new world number one fall at China Open - ABC News & Headlines – Australian Broadcasting Corporation

Kimberly Birrell was a second-round casualty at the China Open. (Getty Images: Robert Prange)

Australian women's involvement at the China Open is down to just one singles player after Kimberly Birrell and Storm Hunter were both second-round casualties.

World number 41 Birrell suffered a 6-4, 6-4 loss to Czech Marie Bouzkova at the WTA 1000 event in Beijing on Saturday night. 

Birrell, 28, who won the Korea Open last Sunday with a win over compatriot Maya Joint in the final, raced out to a 3-1 first-set lead before dropping serve twice to lose it in 42 minutes.

Down 3-0 in the second, Birrell lifted and won the next four games but was broken twice more to see her involvement in the Chinese capital come to a premature end.

For Bouzkova, the 28-year-old 18th seed, a meeting with China's Zheng Qinwen awaits.

The 2024 Olympic champion was leading Anna Kalinskaya 6-7 (4/7), 6-4, 3-0 when the Russian retired. 

Earlier, Queensland veteran and former doubles world number one Storm Hunter was beaten 6-2, 6-2 by Maria Sakkari in just 73 minutes.

The 182nd-ranked Hunter failed to join 20-year-old fellow Aussie Taylah Preston in round three, losing serve six times in her latest hardcourt tournament clash in Asia.

Next up for Sakkari, the Greek 25th seed and former world number three, is Elina Svitolina.

The sixth-seeded Ukrainian came from a set down to eliminate Czech Katerina Siniakova, 1-6, 6-4, 6-2.

Shock of the day came with newly crowned world number one Elena Rybakina crashing out ‌3-6, 6-4, 6-3 to unseeded Alina Charaeva in the second round.

It couldn't have been a worse start to her reign as the number one as Rybakina lost in her first match since defeating four-times major winner Aryna Sabalenka to capture the US Open title last month.

Charaeva, a 24-year-old Russian-born Armenian ranked 118th ​in the world, etched her name into the record books by becoming the lowest-ranked competitor since the introduction of the WTA rankings in 1975 to rally from a set down to defeat a world number one.

Elsewhere, there were wins for third seed Coco Gauff, eighth seed Iga Swiatek, 21st seed Ann Li and 24th seed Jelena Ostapenko.