Serbian third seed Viktor Troicki and Spanish fifth seed Fernando Verdasco advanced to the third round of the rain-hit $1.4 million ATP Washington Classic with victories on Thursday morning.
World No. 15 Troicki, whose only ATP title came last year at Moscow, fired 13 aces in ousting American Ryan Harrison 7-5, 6-2 while Verdasco, seeking his sixth ATP crown, beat Australian qualifier Marinko Matosevic 6-4, 6-4.
Six second-round matches were pushed to Thursday by rain, including French top seed Gael Monfils facing American Ryan Sweeting and reigning Asian and Commonwealth Games champion Somdev Devvarman of India meeting seventh-seeded Cypriot Marcos Baghdatis.
Russian former World No. 3 Nikolay Davydenko, now ranked 30th, beat Aussie qualifier Matthew Ebden 6-3, 7-5, to book a third-round date with Verdasco.
Davydenko beat then-top-ranked Rafael Nadal in the Doha semi-finals and won his 21st career ATP title in April at Munich, but lammented his inconsistency against lesser players.
"Now I'm losing to wildcards, qualies and 100-something players. I feel like I can't find my game like before," he said. "Maybe confidence. With some luck I'll win some tournaments and my confidence will come back."
At age 30, the Russian who won five titles in 2009 including the ATP World Finals is fighting to prove he can still be a contender.
"I need to prove a lot. Mentally I'm still down," Daydenko said. "I feel I can play. I don't want to retire."
Czech Radek Stepanek advanced in 57 minutes with a 6-1, 6-1, triumph over American Wayne Odesnik, who was playing in his first ATP match since being banned last year for pleading guilty to importing human growth hormone to Australia.
"It has rejuvenated my career, because I'm a lot hungrier," Odesnik said, adding that he has no regrets for his actions and that rebukes from rivals that his ban was too short "don't matter to me. They don't know the facts."
Odesnik held serve just before rain halted play, and when the match resumed Stepanek won the next 11 games in a row to book a third-round date with Finn Jarkko Nieminen.
Two rising US talents won by retirement. Michael Russell eliminated Xavier Malisse 7-6 (7/4), 2-3 when the Belgian retired with a sore right arm and Donald Young ousted fourth seed Jurgen Melzer 6-7 (6/8), 6-4, 3-1 when the Austrian retired.
During a rain delay, Melzer said he would not resume play due to a pulled muscle in his left leg.
"You would like to win the last point but I felt like I put him in that position," Young said. "If he felt he could have won he would have come back."
Young, a 22-year-old left-hander, will face Russell to decide a berth in what would be only the second quarter-final of Young's ATP career.