OEIRAS, Portugal -- Former U.S. Open champion Juan Martin del Potro got by Pedro Sousa 6-2, 3-6, 6-3 in the first round of the Estoril Open on Tuesday.
The eighth-seeded Argentine made his season debut on clay. He broke his opponent's serve in the third and seventh games to take the first set in under half an hour.
But Del Potro's double-fault in the eighth game of the second set helped Sousa, of Portugal, even the match.
Del Potro double-faulted again to lose his service in the first set of the opening game before breaking back twice. He is working his way back up the rankings after undergoing wrist surgery almost a year ago.
Sixth-seeded Thomaz Bellucci of Brazil defeated Frederik Nielsen 7-5, 6-1.
In the women's competition, fourth-seeded reigning champion Anastasija Sevastova went out as Urszula Radwanska rallied for a 5-7, 7-6 (5), 6-1 win.
Second-seeded Jarmila Gajdosova of Australia and third-seeded Czech player Klara Zakopalova both advanced after straight-set victories over Renata Voracova and Beatriz Garcia Vidagany, respectively.
Eighth-seeded Greta Arn, the champion in 2007 when the Hungarian came through qualifying, overcame Portugal's Maria Joao Koehler 6-2, 3-6, 6-3.