Union Comercio climbed to an early lead at the top after crushing newly promoted Los Caimanes 4-0 at the Estadio del IPD.
Antonio Meza Cuadra gave the hosts the ideal start, heading in a Jesus Chavez free-kick from the left in the 29th minute as goalkeeper Fernando Martinuzzi was caught in no-man's land.
It took until seven minutes into the second half for Walter Aristizabal's men to double their lead thanks to a fine individual effort by Cristian Bogado.
Bogado shook off his marker down the right and skipped past another defender before composing himself to finish through Martinuzzi's legs from close range.
Another goal from a set-piece followed three minutes later as Walter Moreno headed in Juan Iglesias' curling delivery.
Wilber Huaynacari saw red for Union Comercio in the 77th minute, picking up a second yellow card for a silly challenge in the middle of the park.
But the hosts managed to add to the scoreboard even with 10 men as Mario Velarde struck with a neat finish in the 85th minute.
Crowned champions in December last year, Universitario opened their campaign with a 3-0 win at home to Sport Huancayo.
Christopher Gonzales scrambled in the opener in the 14th minute for Jose del Solar's men before Manuel Ruidiaz tapped in to make it 2-0 midway through the first half.
Cristian Davila's close-range header on the half-hour mark was what completed the scoring, but both teams were reduced to 10 men late on as Nestor Duarte and Cesar Ruiz saw red.
Real Garcilaso were also among the winners on the opening matchday, beating Leon de Huanuco 3-1 as both teams finished with 10 men.
Juan Aurich sit fourth and were the only other team to claim a win, overcoming newly promoted San Simon 2-1.
Elsewhere, Cesar Vallejo had a man sent off late in a 1-1 draw at Universidad San Martin and Cienciano were reduced to 10 men but held on for a 0-0 draw at Melgar.
A 10-man Inti Gas drew 1-1 at home to Alianza Lima and there were three red cards as Sporting Cristal and UTC Cajamarca played out a 1-1 draw.
