A penalty from Fabio Ramos and a header from Victor Ferreira gave Garcilaso a two-goal lead in the first half and although Sporting hit back after the break through Irven Avila, the home side held on for victory and a seven-point lead in Group A.
Garcilaso have 62 points from 34 games, while Sporting have played one less match for 55, two points ahead of third-placed Alianza Lima, who defeated Melgar 2-0.
In Sunday's game at Garcilaso's Estadio Municipal de Urcos, the home side hit the front in the 25th minute when Ramos smashed his spot-kick past the outstretched hands of Sporting's goalkeeper Diego Penny.
It was 2-0 three minutes later as Ferreira headed home at the back post from Jose Fernandez's right-wing cross.
Sporting scored on the counter-attack in the 50th minute when Avila stepped past Garcilaso's Diego Carranza to finish, after picking up a pin-point pass from Horacio Calcaterra, but the visitors could not manage an equalising goal and Garcilaso held on for the three points.
