Third seed Jelena Jankovic suffered a shock second round exit from the Sony Ericsson Open at Key Biscayne, Florida, after losing 4-6, 6-7 (5) to Argentine Gisela Dulko.
Top seeds Serena Williams and Rafael Nadal eased through and the surprise came in the final match of the round.
Dulko, ranked 35th in the world, produced an inspired display to prevail in a second set tiebreak against Serb Jankovic, who was clearly struggling with her game.
Jankovic looked to have turned the corner when she broke serve in the sixth game of the second set but Dulko broke back in the ninth and the set went to a dramatic tie-break.
The tall Serb was 5-2 up but let her rival back into the match with a double-fault and never recovered.
"I haven't been playing well at all. I've been losing to players because I'm just not at my level," she said.
"I'm not the same player as I used to be. I've lost a couple of matches which for a player of my caliber it's not really acceptable and so I lost a little bit of confidence. That showed today in the match."
Nadal's game was preceded by a flamenco dancer on the stadium court, but there was little need for fancy footwork from the Spaniard as he enjoyed a routine 6-2, 6-2 win over Russian Teimuraz Gabashvili.
The Spaniard will now face Portugal's Frederico Gil in the next round.
Williams, searching for her sixth win at Key Biscayne, did not sparkle but still had little trouble in her 6-2, 6-3 victory over Alexa Glatch.
Having dealt with the 19-year-old Californian, a wildcard entry, Williams will now play China's Peng Shuai, seeded 32nd, who beat Italian Mara Santangelo 7-5, 6-3.
"I definitely think I could have played better. But I had a few little jitters going out there - no one wants to go out in their first match," said Williams.
Serena's sister Venus got off to a slow start but found her form to defeat spirited Israeli Shahar Peer 6-3, 6-3 and ensure a meeting with German Anna-Lena Groenefeld in the next round.
Two other Chinese players, Li Na and Zheng Jie, also advanced with straight-set victories. Li surprised 29th seed Aleksandra Wozniak of Canada, 7-5, 6-3 while Zheng, seeded 17th, saw off Germany's Julia Goerges 6-4, 6-2.
Fourth seed Andy Murray of Britain had to graft for his 4-6, 6-3, 6-2 win over Argentine Juan Monaco.
(Agencies via Shanghai Daily March 30, 2009)
