Second seed Sloane Stephens was upset by Russian Olga Puchkova, 7-5, 6-3, in first-round play Monday at the $235,000 Citi Open tennis event.
Stephens, who was playing her first match since falling to Marion Bartoli in the Wimbledon quarterfinals, was broken three times in the opening set and then faltered in the second. The American was on court only 1 1/2 hours.
Reigning champion Magdalena Rybarikova was a come-from-behind first-round winner. The seventh-seeded Slovak overcame American Christina McHale 2-6, 6-4, 6-2 on the hardcourts at FitzGerald Tennis Center.
Rybarikova beat Russian Anastasia Pavlyuchenkova in last year's finale.
Additional wins came for Argentine Paula Ormaechea, Germany's Andrea Petkovic, Slovakia's Jana Cepelova and American Melanie Oudin, who topped Australian Anastasia Rodionova, 7-5, 6-3.
This week's top seed is German left-hander Angelique Kerber.
The 2013 Citi Open champ will collect $40,000.