Davydenko recorded his 50th match victory of the season by ousting Chris Guccione 6-4, 6-4. It is the fourth straight season Davydenko has won at least 50 matches.
Verdasco rallied to defeat qualifier Tiemuraz Gabashvili 1-6, 6-4, 6-4. Verdasco fell to Andy Murray in the 2007 championship match.
Fourth-seeded Mikhail Youzhny coasted into the second round with a 6-2, 6-1 win over Ivan Navarro, but No. 5 seed Marin Cilic was upset by Mikhail Kukushkin 7-6 (7-4), 7-6 (8-6).
Other first-round winners included Jeremy Chardy, Ernest Gulbis and Janko Tipsarevic.
Murray, coming off his fourth title of the year in Madrid last week, will put his No. 1 seed on the line Wednesday against Sergiy Stakhovsky.