The American was given a tough draw against Serbia's Bojana Jovanovski and, after losing the second set in a closely fought tie-break, she eventually came through 6-2 6-7 (8/10) 6-4 in two hours 37 minutes.
Britain's Elena Baltacha made a winning return to the WTA Tour following a long lay-off with a foot injury as she saw off Stefanie Voegele of Switzerland in two close sets.
Baltacha took the opener after another lengthy tie-break and recovered from a break down in the second, winning five straight games to complete a 7-6 (11/9) 7-5 win lasting two hours.
Slovakian Jana Cepelova needed three sets to get past Lesia Tsurenko of Ukraine, with two of them decided by a late break as Cepelova won 5-7 6-3 7-5.
Olga Govortsova went through in more comfortable fashion, the Belarusian beating Holland's Arantxa Rus 6-2 7-5.
Darkness forced the suspension of Sloane Stephens' clash with Tsvetana Pironkova at 2-2 in the final set. American rising star Stephens won the first 6-3 before being pegged back, Pironkova taking the second set 6-2.