Robredo, who won this tournament three years ago, received a first-round bye before being ousted 3-6, 7-6 (10-8), 6-4.
Defending champion Horacio Zeballos reached the second round with a 6-3, 6-3 decision over Gonzalo Lama and the opening round was completed when fifth-seeded Jeremy Chardy defeated Christian Garin 7-5, 6-0.
Zeballos won his only ATP championship here last year when he stunned Rafael Nadal in the finals.
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