Former top-five star and three-time champion Nikolay Davydenko suffered a first-round upset Tuesday at the Kremlin Cup tennis event.
The fifth-seeded Davydenko gave way to fellow Russian Alex Bogomolov Jr. 7-5, 6-4 indoors at Olympic Stadium. Davydenko titled here in 2004, 2006 and 2007.
Seventh-seeded Argentine Carlos Berlocq avoided an upset by overcoming Russia's Andrey Kuznetsov 1-6, 6-4, 6-3 on Day 2.
In other opening-round action, Russian qualifier Konstantin Kravchuk defeated Kazakhstani qualifier Evgeny Korolev 6-4, 6-3 and Dutchman Igor Sijsling grounded German qualifier Michael Berrer 7-6 (9-7), 6-3.
In a second-round affair on Wednesday, third-seeded 2010 champion and last year's Moscow runner-up Viktor Troicki will take on Tunisian Malek Jaziri. Troicki lost to fellow Serb Janko Tipsarevic in last year's finale.
This week's champion will take home $121,520.