Paul Capdeville of Chile upset fifth-seeded David Nalbandian 6-2, 6-2 Monday in the first round of the Estoril Open.
Nalbandian, the 2002 and 2006 champion, was broken once in each set to lose in 52 minutes.
The Argentine, who won the Sydney International in January, had injured a hip at the Barcelona Open last month.
On the women's side, top-seeded Iveta Benesova of the Czech Republic edged Neuza Silva of Portugal 6-4, 5-7, 6-4.
The 29th-ranked Benesova improved to 15-11 this year.
Third-seeded Jarmila Groth of Slovakia rallied to defeat No. 4 Mathilde Johansson of France 1-6, 6-1, 6-1.