Australia's Chris Guccione has crashed out to Woong-Sun Jun in the opening round of the Indianapolis Tennis Championships.
Guccione lost an break of serve early in the first set and never recovered, as the Korean qualifier went on to register a 6-4 7-6 (7-4) victory.
Top seed James Blake advanced to the second round with a 7-6 (7-2) 6-2 defeat of Israel's Dudi Sela.
The American, who recently made second-round exits at both the French Open and Wimbledon, is seeking an 11th career title.
The 28-year-old, who has won five of his 10 career titles on US soil and twice reached the US Open quarter-finals, won this event in 2006.
His title defence ended in the last eight last season, when Sam Querrey, another American, defeated him in a match that saw all three sets decided on tie-breaks.
Querrey, the fourth seed, opened play with a 6-4 6-4 victory over Japan's Go Soeda.
Other seeded players in action were fifth seed Tommy Haas, sixth seed Fabrice Santoro and eighth seed Thomaz Bellucci.
Haas advanced with a 7-6 (7-4) 6-2 victory over Jesse Levine, but Santoro and Bellucci were not as fortunate.
Haas, who advanced to the quarter-finals in 1996 and the semi-finals here in 2002, saved eight of the nine break point chances he faced.
"It's always difficult when you play each other for the first time in a match," Haas said.
"We've known each other for quite a long time and we practice together once in a while, but a match is a totally different story."
"I played a couple of good points late in the tie-break to get it going my way."
A 35-year-old Frenchman, Santoro entered this event fresh off claiming the sixth title of his career on Sunday in Newport.
He will not have the chance for two in a row after Rajeev Ram sent him packing with a 7-6 (8-6) 6-4 triumph.
"It was certainly a quality win," Ram said.
"He doesn't really give you anything, so putting together two sets of good tennis is great."
Bellucci won the first set against Alejandro Falla before the Colombian rebounded to post a 3-6 6-4 6-1 victory.
Other winners included Vincent Spadea, Bobby Reynolds, Wayne Odesnik, John Isner and Jun.
With the win, Jun gets a meeting with Blake in the second round.
Isner, who had 21 aces in a 7-5 6-4 victory over Robert Kendrick, will meet Haas.
Spadea, who celebrates his 34th birthday on Saturday and reached the Indianapolis final in 1999, cruised past 18-year-old Donald Young in an all-American contest, needing just 51 minutes to post a 6-2 6-4 win.
Indianapolis Tennis Championships, Indiana Results - Day 2
Men’s Singles First Round
1-James Blake (USA) d Dudi Sela (ISR) 7-6 (7-2) 6-2
4-Sam Querrey (USA) d Go Soeda (JPN) 6-4 6-4
5-Tommy Haas (GER) d Jesse Levine (USA) 7-6 (7-4) 6-2
Rajeev Ram (USA) d 6-Fabrice Santoro (FRA) 7-6 (8-6) 6-4
Alejandro Falla (COL) d 8-Thomaz Bellucci (BRA) 3-6 6-4 6-1
Wayne Odesnik (USA) d Aisam Qureshi (PAK) 6-4 7-5
Bobby Reynolds (USA) d Frank Dancevic (CAN) 6-7 (7-6) 6-3 6-2
John Isner (USA) vs Robert Kendrick (USA) 7-5 6-4
Vince Spadea (USA) d Donald Young (USA) 6-2 6-4
Woong-Sun Jun (KOR) d Chris Guccione (AUS) 6-4 7-6 (7-4)