Anna Chakvetadze caused an upset in the opening round of the Pilot Pen tournament in Connecticut as she toppled fourth seed Nadia Petrova.
Chakvetadze looked set for an emphatic defeat as the unseeded Russian lost the first set 6-0.
However she hit back in style to win the second set on a tie-break before winning the decider 6-4 to progress.
Sybille Bammer is through after beating Spain's Anabel Medina Garragues 7-5 6-4.
And she is joined by Alona Bondarenko in the next round after the Ukrainian came back from a set down to beat Meghann Shaughnessy 4-6 6-3 7-5.
