The ninth-seeded German fell to China's Li Na in the 2012 event and began her quest to return to the final with a 6-7 (6-8), 6-0, 6-1 triumph over her Italian opponent.
Also logging a Day 1 victory was American Venus Williams, who cruised into the second round with a 6-4, 6-1 triumph against Slovakian qualifier Jana Cepelova in just her second tourney since a first-round loss at the French Open.
Meanwhile, 11th-seeded Australian Samantha Stosur downed Russian Svetlana Kuznetsova, 6-1, 7-5, and No. 12 Roberta Vinci of Italy moved on with a 6-4, 5-7, 6-3 decision over American wild card Bethanie Mattek-Sands.
Elsewhere, No. 16 Russian Maria Kirilenko outlasted Georgian qualifier Anna Tatishvili, 4-6, 7-6 (7-4), 7-6 (7-4) while Sloane Stephens held off Croatian qualifier Petra Martic 6-2, 3-6, 6-3, drawing former world No. 1 Maria Sharapova as her next opponent.
Other Monday winners included Americans Vania King and wild card Lauren Davis, qualifiers Marina Erakovic of New Zealand and Eugenie Bouchard of Canada, and Romanian Simona Halep.