Fifth-seeded Australian Marinko Matosevic on Monday joined rising countryman Nick Kyrgios as a first-round loser of the US National Indoor Championships.
Czech Jiri Vesely made short work of 54th-ranked Matosevic with a 6-3 6-2 win.
Vesely, ranked 81 in the world converted four of seven break-point chances to notch his second ATP Tour match win.
Matosevic, who reached the semi-finals last year in his Memphis debut, wasn't the only seed to fall on the first day of competition in the $US647,000 ($A726,000) tournament.
US veteran Michael Russell rallied from a set down to beat seventh-seeded Michal Przysiezny of Poland 3-6 6-3 6-1.
Russell, 35, posted his first ATP match win of 2014 and next faces American Tim Smyczek, who beat Australian talent Nick Kyrgios 6-7 (5-7) 6-4 6-3.
Reigning champion Kei Nishikori of Japan is the top seed, but won't launch his title defence until the second round after enjoying a first-round bye with second-seeded Feliciano Lopez of Spain, No.3 seed Lleyton Hewitt and fourth-seeded Lu Yen-Hsun of Taiwan.
Last year, Nishikori didn't drop a set en route to the title, beating Lopez in the final 6-2 6-3.
He arrives in Tennessee for his title defence fresh from helping Japan reach the Davis Cup World Group quarter-finals for the first time with a 4-1 first-round victory over Canada earlier this month.
