Juan Monaco lost an opening-round match for the third time this season, falling to Simone Bolelli of Italy 7-5, 6-2 at the Brazil Open on Thursday.
The 15th-ranked Argentine had his service broken four times in the second-round loss at the indoor, clay-court tournament in Sao Paulo, South America's biggest city.
The 80th-ranked Bolelli needed 1 hour, 16 minutes to defeat Monaco and advance to the quarterfinals in Brazil. Monaco, who had a bye in the first round, lost his opening match at the Australian Open and last week in Vina del Mar, Chile.
Top-seeded Rafael Nadal will play his first singles later Thursday against Brazilian Joao Souza. The Spaniard withdrew from the doubles on Wednesday to rest his injured left knee.