Sweeting, who was considered a surprise winner of the Houston tournament last year, moved on to the second round after ousting the Brazilian 6-3, 7-6 (8-6).
Sweeting served six aces and saved 7-of-9 break point opportunities in the 108-minute match.
Also advancing was Houston native and qualifier Michael Russell, who rallied to beat Spain's Daniel Gimeno-Traver 2-6, 7-5, 6-1. Russell will face top-seeded Mardy Fish on Thursday.
Other first-round winners were Igor Kunitsyn of Russia, Tatsuma Ito of Japan and Italian Paolo Lorenzi.