Both Serena and Venus Williams had a much easier time than Ana Ivanovic at the US Open on Tuesday as the top seed narrowly avoided first-round elimination.
Fourth seed Serena posted a 6-1 6-4 triumph over Ukraine's Kateryna Bondarenko, while seventh seed Venus ousted Australia's Samantha Stosur 6-2 6-3.
Meanwhile, Ivanovic narrowly avoided a stunning upset before emerging with a 6-1 4-6 6-4 victory over Russian Vera Dushevina.
Playing for the first time since pulling out of the Olympic Games with a thumb injury, Ivanovic looked like she would cruise through to the next round after racing to a 5-0 lead and needing just 27 minutes to win the first set against the world's 57th-ranked player.
However, the world number one failed to find her rhythm in the second set when she dropped the final four games and committed 19 of her 40 unforced errors.
Ivanovic, who has never advanced past the fourth round at the US Open, also dropped the first game of the third set with a stunning upset looking possible at the year's final major.
However at 3-3, Ivanovic broke Dushevina's serve before two unforced errors from the Russian gave Ivanovic the crucial break and she held serve for a 5-3 lead.
The pesky Dushevina fought off a match point to hold serve and Ivanovic then needed to save two break points before finally ending the tense affair when her opponent hit a backhander into the net.
Sixth seed Dinara Safina continued her outstanding summer with a 6-3 6-4 thrashing of Kristie Haerim Ahn, while there was an early upset when 11th seed Daniela Hantuchova endured a 6-4 6-2 setback to Anna-Lena Groenefeld.
Other seeded winners included Agnieszka Radwanska, Amelie Mauresmo, Agnes Szavay, Flavia Pennetta, Alize Cornet, Dominika Cibulkova, Nadia Petrova, Nicole Vaidisova, Alona Bondarenko - the sister of Kateryna - and Ai Sugiyama.