Acapulco, Mexico: Luis Horna's defence of his Abierto Mexicano title lasted only two games when he had to retire hurt against fifth-seeded Gaston Gaudio in the first round on Tuesday.Horna, who won his first career title here a year ago and his second this month in Chile, pulled up with a right leg injury while serving at 1-1.For Gaudio, the win ended a string of seven straight opening-round losses dating to October, including five this year. The former French Open champion hadn't won a match since the US Open second round last September. He'll face Argentine countryman Juan-Pablo Guzman in the second round."I'm playing the worst tennis of my life, and a win like this does not help, because I cannot see where I stand, and it doesn't help to build confidence," Gaudio said. "Today, I'm leaving with nothing."Meanwhile, former Acapulco champs Carlos Moya and Agustin Calleri won in straight sets."Two-time former winner Moya beat Mexican wild card Bruno Echagaray 6-3, 6-4, and second-seeded Calleri, the 2003 champ, defeated Alberto Martin of Spain 6-3, 6-2.Third-seeded Nicolas Almagro of Spain, already a semifinalist and quarterfinalist during the Latin American clay swing this month, hit 14 aces in beating 2003 runner-up Mariano Zabaleta of Argentina 6-3, 6-4.Both of the finalists in Buenos Aires two days ago lost. First-time ATP champion Juan Monaco of Argentina fell to sixth-seeded Nicolas Massu of Chile 7-6 (4), 7-5, and Alessio Di Mauro of Italy was beaten by Lukas Dlouhy of the Czech Republic 6-3, 6-2.Bartoli overcomes PinIn women's play, top-seeded Marion Bartoli of France overcame a sluggish start to defeat her compatriot Camille Pin 7-6 (7), 6-2 in the first round.Bartoli was surprised when Pin took a 5-0 lead in the first set but managed to fight back to 5-5. From there, Bartoli forced a tiebreaker and didn't look back.Two other Frenchwomen were winners, fourth-seeded Severine Bremond, beat Ekaterina Dzehalevich of Belarus 7-6 (5), 6-4, and Alize Cornet put out 2004 champion Iveta Benesova of the Czech Republic 7-6 (2), 4-6, 6-3.Two seeds lost. No 7 Sybille Bammer of Austria, who won her first career title in Thailand this month, was knocked out by Italian qualifier Sara Errani 6-2, 7-6 (6), and No. 8, Australian veteran Nicole Pratt, lost to 2-6, 6-3, 6-3 to wild card Melissa Torres Sandoval, who became the first Mexican in seven years to win in the tournament."I've always believe in myself and kept fighting," said Torres, ranked 402. "It's one of the biggest games of my career."Roberta Vinci of Italy, the Bogota winner on Sunday, beat Ashley Harkleroad of the United States 6-3, 6-3; third-seeded Martina Muller of Germany defeated Jill Craybas of the United States 6-4, 6-3; and sixth-seeded Gisela Dulko of Argentina comfortably beat Brazilian Jenifer Widjaja 6-2, 6-2.Three days after they lost in the Bogota semifinals, fifth-seeded Flavia Pennetta of Italy downed Lourdes Dominguez Lino of Spain 6-3, 6-3.