American Danielle Collins overcame former world No.1 Venus Williams in the opening round of the Wuhan Open on Sunday while defending champion Aryna Sabalenka also advanced.

Collins, who had defeated compatriot Williams in their only previous meeting in Miami last year, fired 32 winners to grind out a 7-5 7-6 (7-5) victory over the seven-times grand slam champion.

But Australia’s Ajla Tomljanovic is out, beaten 7-6 (7-5) 6-2 by Ukrainian Dayana Yastremska in a rematch of February’s Hua Hin final.

Tomljanovic’s compatriot, world No.1 Ashleigh Barty, is the top seed and as one of the eight highest-seeded players she has been afforded a first-round bye.

She will open against Caroline Garcia on Tuesday after the Frenchwoman outclassed Daria Kasatkina 6-2 6-2 on Sunday.

Petra Kvitova, Caroline Wozniacki and Angelique Kerber will also feature in the tournament in China.

Collins, 25, meanwhile, will next take on ninth seed Sabalenka, who showed power and precision to get past Belarusian compatriot Aliaksandra Sasnovich 6-1 6-2.

Former US Open champion Sloane Stephens also progressed to the second round with a 7-5 6-4 victory over Zhang Shuai while Elena Rybakina outlasted local hope Zhu Lin 7-5 2-6 6-0.