Top seed Nikolay Davydenko began his bid for a third successive Kremlin Cup title with a 6-1, 7-5 win over Frenchman Florent Serra on Tuesday.
The Russian world number five cruised through the first set in 32 minutes but the 53rd-ranked Serra put up a better fight in the second, holding his serve to stay in the match.
Davydenko, hoping to secure a place in the season-ending Tennis Masters Cup in Shanghai, finally broke Serra's serve in the 11th game to set up a second-round encounter with Spaniard Guillermo Garcia-Lopez.
"My goal is to finish the season in the top five for a fourth year in a row," Davydenko told a news conference.
"And of course, to win another title here in Moscow."
Crowd favourite Marat Safin saw off Israeli qualifier Noam Okun in a tough battle 7-6, 3-6, 6-4 in the last match on centre court at Moscow's Olympic sports complex.
Earlier, French pride suffered another beating when Uzbek qualifier Denis Istomin upset sixth seed Michael Llodra 7-6, 6-3.
The women's sixth seed Venus Williams was also sent packing, beaten by Italy's Flavia Pennetta 6-4, 2-6, 6-4. The Wimbledon champion had mostly herself to blame for the defeat, committing 38 unforced errors and seven double faults in a two-hour match.
Fifth seed Svetlana Kuznetsova, however, again avenged her Olympic defeat by Li Na by beating the Chinese 6-4, 7-5. Li shocked the Russian in the first round of the Beijing Games in August, though Kuznetsova beat her in the Pan Pacific Open the following month.
"I knew she was a tough nut to crack so I'm happy to win in straight sets," Kuznetsova said.
"I'm still not totally satisfied with my game, though ,but I hope it gets better in the later rounds."
Next up for the former US Open champion is Italian qualifier Sara Errani, who knocked out world number 17 Victoria Azarenka of Belarus 1-6, 6-4, 6-3.
Asked if she would like to follow the lead of compatriot Dinara Safina and cook an Italian dish with Errani, Kuznetsova snapped back: "Cook a dish with Errani? No way, I'd rather make a nice dish out of her on the court."
Second-seeded Safina, who had a bye into the second round along with the other top seeds, Jelena Jankovic, Elena Dementieva and Ana Ivanovic, joined forces with her opponent Amelie Mauresmo to cook a French meal for charity on Monday.
The women's field is the strongest in the Kremlin Cup's 19-year history, with only world number two Serena Williams and number six Maria Sharapova among the leading players absent because of injury.