Sania Mirza failed to recover from a slow start as Jelena Jankovic defeated her in the first round of the Los Angeles Open on Tuesday night.
Jankovic of Serbia and Montenegro beat the Indian teenager 6-2, 7-6 (3) in an hour and 15 minutes to advance to the next round. Sania had also lost her doubles first round with South African partner Liezel Huber on Monday.
Jankovic raced off to a 5-0 lead in the first set as Sania struggled to find her rhythm. The Indian broke to get on the board at 5-1 and kept her service game before Jankovic served out the first set 6-2 in 28 minutes.
The second set ran very close, and went on serve till 4-3. Jankovic got a crucial break to go 5-3 in the lead and a chance to serve for the match.
Sania, however, raised the tempo and won three straight games in a row and go into the lead at 6-5 for the first time in the match.
But she failed to cap the fightback and squandered a set point, before losing the tie-breaker 7-3.
In other matches, former world number one Serena Williams, making her comeback in the tournament, beat eleventh seed Maria Kirilenko (Russia) 6-2, 6-1.
Nadia Petrova became the first big-name casualty on Tuesday with a 6-3, 6-2 loss to Spain's Virginia Ruano Pascual in the second round.
The second-seeded Russian, who has struggled with injury since winning three consecutive titles on clay earlier this year, also lost her opening match at the Acura Classic in San Diego last week.
In first-round upsets, Japan's ninth seed Ai Sugiyama lost to American Laura Granville 7-5, 6-2 and Frenchwoman Nathalie Dechy, the 17th seed, was knocked out by American Meghann Shaughnessy 4-6, 6-4, 6-4 after a three-hour contest.
However, third-seeded Russian Elena Dementieva moved smoothly into the third round with a 6-2, 7-5 win over German Julia Schruff.