Memphis, TN ( - Sam Querrey was defeated by Alex Bogomolov in the first round at the U.S. National Indoor Championships on Tuesday.

The sixth-seeded American Querrey, a 2010 winner at this event, suffered a 2-6, 6-4, 7-6 (9-7) loss at the hands of Russia's Bogomolov at The Racquet Club of Memphis.

Eighth-seeded Mikhail Kukushkin of Kazakhstan held off Russian Teymuraz Gabashvili 7-6 (11-9), 7-5, while capable American Jack Sock advanced by outlasting French left-hander Adrian Mannarino 7-5, 1-6, 7-6 (7-5) on Day 2.

Also on Tuesday, 6-foot-10 Croat Ivo Karlovic beat Aussie Matthew Ebden 7-5, 6-4; Cypriot wild card Marcos Baghdatis handled American Rajeev Ram 6-3, 6-4; German Benjamin Becker leveled Slovak Lukas Lacko 6-3, 6-2; American Ryan Harrison breezed by German Bjorn Phau 6-3, 6-4 and American Alex Kuznetsov dropped Belgian fellow qualifier David Goffin 6-4, 6-3.

This week's top seed is reigning champion Kei Nishikori, who beat this week's second seed, Feliciano Lopez, in last year's Memphis finale. Nishikori will meet Becker in the round of 16.