Daria Gavrilova has positioned herself nicely for a run at the China Open with an upset win over US Open semi-finalist Coco Vandeweghe.

Her Australian No.1 ranking under siege from Ashleigh Barty, Gavrilova responded with an important second-round victory over the Pat Cash-coached Vandeweghe.

Gavrilova was leading 6-3 2-0 on Tuesday when the seeded American retired with a back injury.

The 23-year-old next plays Czech Barbora Strycova – a 6-4 6-2 victor over Julia Goerges – for the right to take the path of eliminated top seed and world No.1 Garbine Muguruza.

Every win in Beijing is huge for Gavrilova and Barty as they chase spots in the season-ending Elite Trophy, which will feature players ranked from ninth to 20th who missed out on the eight-player WTA Championships in Singapore.

Gavrilova and Barty – fresh from her charge to last week’s Wuhan Open final – are separated by just one place in the rankings at 22nd and 23rd in the world respectively.

Gavrilova’s victory on Tuesday came after world No.2 Simona Halep, five-time grand slam champion Maria Sharapova and 12th seed Petra Kvitova also progressed to the last 16.

Halep was leading Magdalena Rybarikova 6-1 2-1 when the Slovak retired.

Sharapova beat fellow Russian Ekaterina Makarova 6-4 4-6 6-1 and Kvitova ousted Varvara Lepchenko 6-4 6-4.

In other second-round matches, Daria Kasatkina defeated Lara Arruabarrena Vecino 6-4 7-5 and Elena Vesnina beat local wildcard Duan Yingying 6-3 6-2.

Barty faces third seed Elina Svitolina on Wednesday, with the winner to meet Vesnina for a place in the quarter-finals.