The Dynamo and Municipal played to a scoreless tie in the first game of the quarterfinal series a week ago in Guatemala.
That defensive play continued for both teams in the scoreless first half Wednesday. Houston managed only two shots on goal in the first 45 minutes, while Municipal had one.
But De Rosario changed that quickly in the second half. In the 46th minute, he dribbled in from the left side, got bumped by two defenders and turned a circle inside the box. When he came out of the crowd, De Rosario found himself wide open for a shot from 3 yards out.
De Rosario then made it 2-0 in the 69th minute on a penalty kick from 10 yards out. It came after a foul by Municipal's Claudio Albizures inside the box.
Houston made it 3-0 in the 73rd minute when Chris Wondolowski took a crossing pass from Corey Ashe to score from short range. Brian Ching also got an assist on the play.
Municipal got on the scoreboard in the 85th minute on a short penalty kick by Guillermo Ramirez. The penalty was a handball call on Wade Barrett.