Heather Watson and Harriet Dart were beaten by fellow Briton Naiktha Bains and Czech Tereza Martincova 4-6 6-3 10-5 in the Birmingham Classic doubles first round.

China's Zhang lost to Britain's Johanna Konta in the Nottingham Open last week.

Belgian top seed Elise Mertens, 25, was beaten 7-6 (7-5) 6-7 (5-7) 7-6 (7-4) by Australia's Ajla Tomljanovic.

But second seed Ons Jabeur advanced, with the 26-year-old Tunisian beating America's Caty McNally 6-4 6-2 on her debut at the tournament.

"I like playing on grass - I like all the slicing, but it takes some time to get used to and I feel like I'm on a football pitch," she said.

"There are no grass courts in Tunisia, only football fields. Maybe I can play on those!"

Towards the end of the day, Russian fourth seed Daria Kasatkina had to come from a set down against Slovenia's Polona Hercog to win 4-6 6-3 6-3 to make it three out of the top four seeds to advance.

Play starts at 11:00 on Wednesday, with Watson and Zheng scheduled last on the Ann Jones Court.

Watson is still looking for back-to-back wins in 2021, and until last week in Nottingham, 32-year-old Zhang had won just one match this season.