Baltacha is ranked nearly 300 places behind Schruff

South beat Alicia Molik 1-6 6-3 7-6 in the first round late on Monday after O'Brien and Baltacha had won through from qualifying to reach the main draw.

O'Brien sealed her place with a 7-6 2-6 6-2 win over American Jill Craybas while Baltacha cruised past Germany's Julia Schruff 6-1 6-1.

Wildcard entry Anne Keothavong is the fourth British player in the draw.

Elena Baltacha's GR8 tennis challenge

"I played a fantastic game and I'm just so happy to be back after injury," said ex-British number one Baltacha.

Baltacha, 23, has suffered a series of injury and illness problems since losing the top British ranking three years ago.

"It was a big operation last year and I was still having some problems in January but my surgeon said the epidural he gave me in March can be done again every six months and there will be no long-term dangers," she said.

British number three South defied her lowly ranking of 204 to see off Australia's world number 74 Molik - a win to rival her defeat of 11th seed Francesca Schiavone at Wimbledon last year.

"This was almost as exciting and after seeing the other girls win it was great to complete a really good day for British tennis," said the 21-year-old from Surrey.

O'Brien, 21, added: "I had just come off court when I heard Elena had won as well and it's a great couple of results for British women's tennis."