David Nalbandian was a convincing first-round winner at the Legg Mason Tennis Classic, but former champion James Blake was defeated in Washington.
Argentina's Nalbandian claimed a 6-4 6-0 win over Rajeev Ram in 52 minutes as he made his first ATP Tour appearance since April, but his fellow wildcard Blake - winner of the event in 2002 - was beaten 3-6 6-3 6-4 by qualifier Ryan Sweeting.
Sweeting will next play Michael Llodra, the 14th seed, while Nalbandian is to meet seventh seed Stanislas Wawrinka.
Qualifier Grega Zemlja defeated Benjamin Becker 6-2 6-3 and will next meet three-time champion and 2009 runner-up Andy Roddick, who received a first-round bye.
Number one seed Tomas Berdych, who also received a direct place in the second round, will meet Dmitry Tursunov, who defeated Teymuraz Gabashvili 5-7 7-5 6-4 in two hours 42 minutes.
Denis Istomin was a 6-4 5-7 7-6 (7/5) victor over Leonardo Mayer and will now play fourth seed Marin Cilic.
Viktor Troicki beat qualifier Kevin Kim 6-1 6-2, Michael Berrer defeated Karol Beck 6-3 6-4 and Illya Marchenko claimed a 6-4 3-6 6-4 win over Rainer Schuettler.
Igor Kunitsyn beat fellow qualifier Kei Nishikori 6-2 6-3, while Thiemo de Bakker beat Lukas Lacko 5-7 6-3 6-3.