Manotas has now scored or assisted in 13 of the last 15 games for the Dynamo. The two teams play for possession of El Capitan, an 18th century mountain howitzer cannon with the winner determined by whichever team earns the most points in their regular-season matches. The second leg is Aug. 24 at Toyota Stadium in Frisco, Tex.
Houston took a 1-0 lead in the 20th minute on Manotas' penalty kick after Alberth Elis was tripped by Carlos Gruezo while cutting toward the middle of the box. Manotas then drilled a shot under a diving Gonzalez into the left side of the net.
FC Dallas nearly tied it in the 42nd minute when Michael Barrios drilled a straight-on shot from the left side of the box that Willis deflected with both hands. Jesus Ferreira then fired a rebound shot from near the right post that a scrambling Willis also stopped.
Willis came up with another big save in the 51st minute on a right-footed shot by Bryan Acosta from the top of the box that Willis deflected over the crossbar with a leaping one-hand save.
The Dynamo then upped their lead to 2-0 in the 58th minute when Manotas redirected Memo Rodriguez's crossing pass from the right side of the box past Gonzalez for his fifth goal of the season.
Badji then put FC Dallas on the scoreboard in the 87th minute when he redirected a crossing pass from Barrios from the right side of the box into the middle of the net for his first goal of the season. FCD nearly tied it in stoppage time when Santiago Mosquera redirected a free kick into the net but the goal was quickly waived off for being offside.