The fifth-seeded Davydenko -- who won the Moscow event in 2004, 2006 and 2007 -- succumbed to fellow Russian Alex Bogomolov Jr. 7-5, 6-4 during the Day 2 competition.
No. 7 seed Berlocq, meanwhile, had to overcome a slow start to rally for a 1-6, 6-4, 6-3 victory over Russia's Andrey Kuznetsov in order to advance at Olympic Stadium.
Also Tuesday, the Netherlands' Igor Sijsling bested German qualifier Michael Berrer 7-6 (9-7), 6-3 and Russian qualifier Konstantin Kravchuk got past Kazakhstani qualifier Evgeny Korolev 6-4, 6-3.
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