Peru Primera Division Wrap: Real Garcilaso beaten
In a heated contest that featured eight yellow cards, Cesar Vallejo scored the only goal of the game through Daniel Chavez on 79 minutes, handing Garcilaso their sixth loss of the campaign.
Freddy Garcia's side lead the first phase by an unassailable four points with only one game left to play.
Universitario locked in second position after a 1-0 win at Union Comercio.
Comercio had lost their past three games and it was not to get any better as defender Renzo Reanos scored an own goal, handing Universitario the three points.
The race for the third is still between four clubs after Sporting Cristal were beaten 2-1 by bottom side Jose Galvez.
With Jose Galvez having won none of their past seven games, it was no shock when Cristal's Jose Fernandez put his side into the lead on 17 minutes.
But Jose Galvez fought back with the equaliser four minutes later through Junior Aliberti before midfielder Jersson Vasquez scored the all-important winner in the 84th minute.
Cesar Vallejo, Alianza Lima and UTC Cajamarca can also finish in third position if results go their way.
Alianza Lima earned their chance with a 2-1 triumph against Leon de Huanuco while Cajamarca missed the opportunity to go outright third after losing 3-1 at Cienciano.
In other results, Sport Huancayo thrashed Pacifico 3-0, Universidad San Martin drew 1-1 with a 10-man Melgar and Juan Aurich shared the points with Inti Gas with a 1-1 scoreline.