Defending champion Andy Roddick was beaten by Xavier Malisse, 7-6 (8), 7-5, in an opening-round match on Wednesday at the Regions Morgan Keegan Championships.
For Roddick, whose world ranking has slipped to 27th, it was his earliest exit from the Memphis tournament in 12 appearances. Veteran Malisse, ranked 75th, was winless in four matches this season and in nine career matches against Roddick.
Roddick, seeded No. 2, has been slowed by hamstring and ankle problems this season. He was unable to capitalize on two set points in the first and was broken in the last game of the second by the 31-year-old Belgian.
Olivier Rochus of Belgium and Philipp Petzschner of Germany also pulled off upsets on Wednesday.
Rochus beat No. 5 Alex Bogomolov of Russia, 1-6, 6-4, 7-6 (5) and Petzschner defeated No. 6 Julien Benneteau of France, 7-6 (5), 7-6 (6).
No. 4 seed Milos Raonic, champion of last week's ATP World Tour event in San Jose, plays in a late match on Wednesday.
In other men's first-round matches, No. 3 seed Radek Stepanek won 6-3, 6-2 over qualifier Bobby Reynolds, No. 7 seed Kevin Anderson advanced with a 7-5, 6-3 victory over qualifier Robby Ginepri and Jurgen Melzer of Austria beat Denis Istomin of Uzbekistan, 6-7(2), 6-3, 7-6(4). Istomin was coming off a runner-up finish in San Jose.
In the Memphis International, the accompanying Women's Tennis Association event, Alberta Brianti of Italy eliminated No. 2 seed Ksenia Pervak, 7-6 (3), 6-2, while Sofia Arvidsson, the 2006 champion, joined Brianti in the quarterfinals with a 7-6 (5), 0-6, 6-3 upset of No. 5 seed Pauline Parmentier.
Unseeded Lesia Tsurenko of the Ukraine also reached the quarterfinals by ousting a seed. She beat No. 3 Lucie Hradecka of the Czech Republic, 3-6, 6-4, 7-6 (3).
Only one of the eight women's seeds - No. 4-ranked New Zealander Marina Erakovic - remains moving into Thursday's quarterfinals.