BUENOS AIRES, Argentina -- Unseeded Peruvian Luis Horna upset David Nalbandian 6-4, 6-3 Tuesday night at the Copa Telmex, capitalizing on the error-plagued, top-seeded Argentine who slogged through the 90-minute match.
Horna moved Nalbandian, recovering from a recent leg ligament injury, all over and broke his rival repeatedly as many in the crowd chanted "Argentina! Argentina!" raucously between games of the round-robin group match.
"This is a tough place for a visitor, but the Buenos Aires tournament is one of the greatest and to win against David, well, he is a crack player," said Horna, who was jeered by thousands watching the day's showcase match on the outdoor red clay of the Buenos Aires Lawn & Tennis Club.
Nalbandian led 3-1 in first set before the pair traded several breaks until Horna held for a 5-4 advantage.
Nalbandian then became erratic in the final game, lobbing a shot long, smashing a forehand wide but still managing to fend off a double-break point before dropping the set.
The Argentine went to deuce five times before holding at 2-2 in the second set. Horna had two aces to edge ahead again and then broke Nalbandian for a 4-2 lead as the Argentine committed his second double fault.
Horna served out for the victory, completing the win on his second of two match points.
"There were a lot of unforced errors," Horna said. "It was a long, hard match."
Earlier Tuesday evening, fifth-seeded Spaniard Carlos Moya beat Potito Starace of Italy 6-4, 6-4.
Also Tuesday, Albert Montanes of Spain beat third-seeded Agustin Calleri 6-7 (4-7), 6-4, 6-4 in round-robin play, a week after losing to the Argentine in Brazil.
Calleri, who beat Montanese last week en route to the Costa do Sauipe quarterfinals in Brazil, jumped ahead again Tuesday. But Montanes took a 5-1 lead in the final set before beating back a late rally for his fourth victory over Calleri in five meetings.
Calleri was the Copa Telmex runner-up in 2002, and a semifinalist last year.
In another round-robin match, Nicolas Lapentti of Ecuador overcame seven double faults to defeat Nicolas Devilder of France 6-3, 2-6, 6-3, while fourth-seeded Nicolas Almagro of Spain beat Argentine rival Martin Vassallo Arguello 7-5, 6-4 in another round-robin contest.
In elimination play, Brazil's Flavio Saretta blew past Czech Lukas Dlouhy 6-3, 6-1.
Also Tuesday, Brasil Open winner Guillermo Canas came off his weekend victory in Brazil to defeat fellow Argentine Juan Pablo Guzman 7-6 (7-4), 6-3 in elimination play. The win propelled Canas into the round-robin group that includes Nalbandian.
Canas, who was invited to the Buenos Aires event after his Brasil Open victory, said he arrived weary after upsetting top-seeded Spaniard Juan Carlos Ferrero, 7-6 (7-4), 6-2 to win his first ATP tournament since returning from a doping ban.
Canas, who rejoined the ATP circuit in September following a 15-month doping suspension, powered to a first-set tiebreak victory and then broke Guzman three times in the final set. Guzman, a wild-card entry, saved two of three match points in the final game before finally succumbing.
