Fifth seed Marcos Baghdatis was knocked out in the opening round of the BRD Nastase Tiriac Trophy.
The Cypriot fell 6-2 6-4 to Italy's Marco Cecchinato while eighth seed Paul-Henri Mathieu was another casualty, losing 7-6 (7/0) 2-6 6-1 to Moldovan qualifier Radu Albot.
Seventh seed Paolo Lorenzi did make it through, beating Diego Schwartzman 6-3 6-4.
Dutchman Robin Haase will play top seed Bernard Tomic in round two after a 7-6 (7/4) 6-4 win over Andrea Arnaboldi while there were also wins for Fernando Verdasco, Lucas Pouille, Illya Marchenko and Daniel Gimeno-Traver.
Source: PA