Independiente kept the pressure on league leaders Barcelona with a 4-0 thumping of Universidad Catolica, rising to 27 points - one adrift of the pace-setters from Guayaquil.
Sornoza kick-started Independiente's victory at the Estadio General Ruminahui del Valle de Los Chilos, whipping a dead ball over the wall and past the outstretched right hand of the visitors' goalkeeper in the 54th minute.
The 20-year-old midfielder then teed up the home side's second goal six minutes later with his reverse pass at top speed finding Fernando Guerrero, who finished first time.
Independiente skipper Armando Solis completed the rout with a brace in the last half hour.
Solis' first goal came after Daniel Angulo's header hit the bar with the 27-year-old thumping the rebound into the net, while the striker made it 4-0 in the 89th minute, slaloming his way through Catolica's defence to score.
Independiente (11) have played one less match than Barcelona (12) so far this season in the Primera A, while they have a seven-point lead on third-placed Emelec, who also have a game in hand on the leaders.