Rolando Bogado scored the only goal as Peruvian side Real Garcilaso beat Nacional of Uruguay 1-0 in the first leg of their Copa Libertadores last-16 tie.
Led by Mauricio Montes and Fabio Ramos, the hosts attacked from the off and were rewarded when Bogado headed home from a corner in the 35th minute.
Substitute Vicente Sanchez had the best chances to equalise after the break but he fired just wide in the 64th minute and failed to convert Pablo Alvarez's cross in the dying seconds.
"We were close to equalising and we deserved it," Alvarez said. "In the first half they were better than us, but in the second we had more of the ball and we were the better side."