Haas, a two-time defending champ, also won in 1999. He beat Andy Roddick in last year's final.
In other first-round action, Australian Chris Guccione defeated American Robert Kendrick 7-6 (8-6), 7-6 (7-5); Frenchman Florent Serra beat Brazil's Marcos Daniel 6-1, 6-2; Swede Jonas Bjorkman beat Chile's Paul Capdeville 6-3, 6-1; and Colombian Alejandro Falla defeated Israel's Dudi Sela, 6-4, 6-2.
Roddick, last week's champion in San Jose, is this week's top seed.
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