Davydenko, ranked as high as No. 3 on the tour in 2006 and 2007, needed just 52 minutes to oust Dolgopolov, who was coming off winning the Citi Open in Washington on Aug. 5.
Dolgopolov, a Ukrainian ranked 16th in the world, committed 26 unforced errors to just three by his Russian opponent.
In other men's action on the tournament's first full day, Andreas Seppi of Italy beat the Netherlands' Robin Hasse 6-4, 6-4; qualifier Jesse Levine beat Donald Young 6-4, 7-6 (2) in a matchup of Americans; Taiwan's Yen-Hsun Lu eliminated Poland's Lukasz Kubot 6-3, 6-0; and American wild card Brian Baker outlasted Philipp Kohlschreiber of Germany 7-6 (7), 7-6 (4).
Also, Serbian Victor Troicki beat Croatian qualifier Ivan Dodig 6-4, 7-5, Spain's Pablo Andujar cruised past Australian qualifier Marinko Matosevic 6-4, 6-3, German Florian Mayer defeated qualifier Fabio Fognini of Italy 7-5, 6-2, and Uzbekistan's Denis Istomin eliminated France's Julien Benneteau 6-3, 6-1.
The women's tournament got under way with a mild upset as 66th-ranked Timea Babos, a 19-year-old Hungarian, knocked out 39th-ranked Varvara Lepchenko of the United States 7-6 (4), 6-4. Babos lost in the final round of qualifying Sunday but reached the main draw when Ana Ivanovic withdrew because of a toe injury.
In other women's action, No. 11 seed Dominika Cibulkova of Slovakia earned a 6-3, 6-4 win over qualifier Akgul Amanmuradova of Uzbekistan; Italy's Mona Barthel beat Spain's Maria Jose Martinez Sanchez 6-0, 6-4; Anabel Medina Garrigues of Spain defeated Romanian Simona Halep 6-3, 6-0; Germany's Julia Goerges won in straight sets over Israel's Shahar Peer 6-3, 6-3; and Sweden's Johanna Larsson beat Australia's Casey Dellacqua 6-1, 6-3.
Also, wild card Camila Giorgi eased past fellow Italian Francesca Schiavone 6-1, 6-3, and Eleni Daniilidou of Greece outlasted Vania King of the United States 6-3, 2-6, 7-6 (6) in a matchup of qualifiers.
Information from The Associated Press contributed to this report.