Goltz snapped a year-long goal drought when he scored against Libertad in November, and it would turn out to be the start of a hot streak for the centre back - he now has six goals in seven games.
The 28-year-old single-handedly put his side in pole position to reach the group stages, with his early strike at Caracas' Estadio Olimpico de la UCV in Venezuela followed up by a late penalty to hand the Copa Sudamericana champions a decisive buffer heading to their home leg in Argentina on February 6.
The winner of the tie will enter Group 3, alongside Cerro Porteno, O'Higgins and Deportivo Cali.
Universidad Chile capitalised on their home leg against Guarani, posting a 1-0 win to take the aggregate lead.
Rodrigo Mora scored the winner for the hosts at the Estadio Nacional Julio Martinez Pradanos.
Universidad are eyeing off a spot in Group 4, with Atletico Mineiro, Nacional and Zamora the teams awaiting the victors.
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