LA PLATA, Argentina: Argentina escaped a shock upset in its Copa America opener Friday when substitute Sergio Aguero's late volley earned the hosts a 1-1 draw with Bolivia. Bolivia soaked up the pressure in the first half before snatching the lead early in the second through Edivaldo Rojas. The hosts had to wait until the 77th minute for the equalizer when Aguero slammed the ball home. Argentina's Lionel Messi was marked tightly by the Bolivian defense and had few chances to shine. “It is not what we expected, now we must improve and we win our remaining (group) matches,” a visibly disappointed Messi told reporters. “Now we need tranquility.” Having weathered a first-half storm at the Ciudad de La Plata stadium, Bolivia stunned Argentina two minutes into the second half when Jhasmany Campos hit a corner low to the near post where Rojas back-heeled it past goalkeeper Sergio Romero. Marcelo Martins looked set to give Bolivia a two-goal lead on the hour when he beat Argentina's offside trap but Romero dived to touch the ball away from the striker's feet then got up to block his second effort. “We had a couple of situations that if we'd put them away we could have won the match,” Bolivia's Argentine-born coach Gustavo Quinteros said. “I think the team settled and were more solid in the final minutes of the first half and almost all of the second,” he told news conference. “For us, after such a short time working together and few matches, this is a good result that motivates us to carry on.” Argentina equalized with 13 minutes left when Nicolas Burdisso chested down a cross from Marcos Rojo and Aguero volleyed home. Minutes after his goal, Aguero might have snatched a win for the hosts but his shot brought a diving save from Bolivia goalie Carlos Arias. The draw was a positive result for Bolivia, said goalscorer Rojas. “This result is very important psychologically for our next match (against Costa Rica),” he told a news conference. In an exciting finish, either side could have snatched victory as Argentina created chances while Bolivia attempted to hit them on the break.