Connecticut - Caroline Wozniacki launched her bid for a fifth straight New Haven WTA title on Monday with a 6-3, 6-3 first-round victory over Russia's Ekaterina Makarova.
Wozniacki, seeded third in a field headed by Wimbledon runner-up Agnieszka Radwanska, needed an hour and 21 minutes to book a second-round clash with Sweden's Sofia Arvidsson, a 6-4, 6-1 winner over lucky loser Melanie Oudin of the United States.
A fifth successive title in the hardcourt tune-up for the US Open would put former world number one Wozniacki in elite company. Only Steffi Graf, Martina Navratilova and Chris Evert have won the same WTA Tour title five or more times in a row.
She improved to 18-0 lifetime at the tournament and extended her career dominance over Makarova, who hasn't managed to win a set from the Dane in their four meetings.
Fourth-seeded French Open runner-up Sara Errani also advanced, rallying from 2-5 down in the second set to seal a 6-4, 7-5 victory over unseeded American Bethanie Mattek-Sands.
Sixth-seeded Dominika Cibulkova of Slovakia also advanced with a 7-5, 6-3 victory over Spain's Anabel Medina Garrigues while seventh-seeded Russian Maria Kirilenko cruised past Shahar Peer of Israel, 6-2, 6-2.
Qualifier Olga Govortsova of Belarus defeated lucky loser Vera Dushevina 6-7 (5/7), 6-4, 6-2 to set up a clash with Poland's Radwanska, who enjoyed a first-round bye as did second-seeded Petra Kvitova of the Czech Republic.
Kvitova will open her campaign against Nicole Gibbs, a US qualifier playing in just her third WTA main draw. Gibbs defeated fellow qualifier Alexa Glatch in three sets, 6-4, 1-6, 6-4.