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.
In Group B, Inti Gas moved within five points of leaders Universitario, who lost their second game in a row.
A penalty from Johan Favo gave Leon de Huanuco a 1-0 victory over Universitario, while Inti Gas overcame Jose Galvez by the same scoreline.
Universitario top Group B with 57 points with Inti Gas on 52, while UTC Cajamarca sit third on 49 after a 3-3 draw against Universidad San Martin.
In other results, Pacifico overcame Union Comercio 1-0, Juan Aurich defeated Cienciano 3-0 and Cesar Vallejo drew 0-0 with Sport Huancayo.
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