OEIRAS, Portugal — Roger Federer faltered in his tuneup for the French Open, losing to defending champion Albert Montanes of Spain 6-2, 7-6 (5) Saturday in the Estoril Open semifinals.

Montanes, seeded fourth, will play for the title Sunday against Frederico Gil, who became the first Portuguese to reach the final after he upset fifth-seeded Guillermo Garcia-Lopez of Spain 6-2, 5-7, 6-3.

Unseeded Anastasija Sevastova of Latvia captured the women's final, downing Arantxa Parra Santonja of Spain 6-2, 7-5 for her first career title.

Federer made 48 unforced errors, mostly on his backhand. The top-ranked Swiss was more consistent in the second set on a damp day following heavy rain, but he blew a 5-2 lead in the tiebreaker in which Montanes won the last five points.

Federer came to Estoril for the first time to get more matches on clay in preparation for his French Open title defense this month. He lost his opening match to 40th-ranked Ernests Gulbis at the Rome Masters and won only two matches in Estoril.