Nick Rimando and Joao Plata led Real Salt Lake to victory in Guatemala, while two Mexican clubs also won.
Real Salt Lake opened its CONCACAF Champions League campaign with an away win, holding on for a 1-0 victory at Municipal on Tuesday.
Joao Plata's early goal gave RSL the edge in Guatemala, although the MLS side needed a strong performance from Nick Rimando to prevail in the feisty encounter.
Rimando made four saves, including a brilliant fingertip one to push Carlos Ruiz's free kick onto the bar in the shadows of halftime.
Plata struck the only goal of the game in the third minute, controlling a clearing header from Municipal's defense on the edge of the box and driving the ball into the bottom corner.