Russian former champions Ekaterina Makarova and Elena Vesnina moved into the second round of the Eastbourne International on Monday.
Makarova, who established herself on the WTA Tour by claiming the title in 2010 as a 100th-ranked qualifier, fought off five first-set points to beat British wild card Tara Moore 7-5, 6-4, and 2013 winner Vesnina beat Britain's Heather Watson 6-2, 6-3.
There were also victories for Germany's Andrea Petkovic, who overcame the challenge of China's Saisai Zheng to win 5-7, 6-2, 6-4, and Canada's Eugenie Bouchard, who dismissed American qualifier Varvara Lepchenko 6-1, 6-2.
Vesnina next plays defending champion Belinda Bencic. The Swiss teenager fell and was forced to retire with a leg injury during her opening match in Birmingham last week, but has declared herself fit and ready to defend her title.
"I have been doing the physio treatment all day," said Bencic. "Yesterday I was practicing, so I should be fine. I still tape it a lot, so it's a little bit hurting but it's okay."
The pre-Wimbledon event features seven former champions, including top seed, 2008 champion and last year's finalist Agnieszka Radwanska of Poland. Italy's Roberta Vinci is seeded two, Bencic is seeded three and Timea Bacsinszky of Switzerland is seeded four.