Kellyn Acosta netted a second-half brace in the opening leg as host Dallas took control of the quarterfinal tie on Thursday.
Despite playing its first competitive game of the year, Dallas had no trouble seeing off the visiting side at Toyota Stadium as Cristian Colman showed his speed to open the scoring in the 30th minute.
After controlling the first half, Acosta increased Dallas' advantage 10 minutes following the interval.
Acosta then made it 3-0 thanks to a powerful shot with four minutes remaining in regulation before a swift counterattacking move saw Michael Barrios slot home the team's fourth of the night.
The second leg is in Panama City on Wednesday.