The fourth-round of the Lamar Hunt US Open began on Tuesday night with three games featuring four Major League Soccer clubs. The Colorado Rapids needed a second-half come back to eased past OKC Energy. Christos FC, the only amateur team remaining in the competition, managed to score an early-goal against DC United before finally “capitulating” late in the encounter to end their storied run. Finally, Seattle Sounders and Portland Timbers renewed their “storied rivalry” as they fielded their USL and reserve players.

Here's a complete rundown of Tuesday's US Open Cup fourth round matches:

Colorado Rapids 3, Oklahoma City Energy 2

Energy pulled-out to a two-goal lead at halftime thanks to goals from striker Daniel Gonzalez on a thirty-eight-minute counterattack and Phillip Rasmussen just before the halftime whistle. However, that two-goal lead didn't stand the test of the second forty-five minutes. Colorado Rapids' come back began straightaway in the second-half with playmaker Dominique Badji scoring in the forty-ninth minute. Later in the sixty-sixth minute, Eric Miller leveled up the scoreline before Dennis Castillo knocked-in an eighty-ninth corner to give Rapids the home win.

Seattle Sounders 2, Portland Timbers 1

Neither team fielded their regular starters, instead, they featured several players from their reserve teams to fill-in the match roster. Seattle Sounders scored the opener in the third minute thanks to an Aaron Kovar's fine finish from close range. Later in the thirty-eight minutes, Portland Timbers leveled up the scoreline with Augustine William's first senior team career goal.

Afterward, A handball inside the penalty box against Portland defender Omar Mohamed eventually allowed the home team to come back through a Zach Mather's brilliant penalty kick finish in the fifty-fourth minute.

DC United 4, Christos FC 1

Mamadou Kansaye brilliantly curved in a close range free-kick to score the opener and astonishingly give Christos FC the lead in the twenty-third minute.

However, midfielder Julian Buescher struck the equalizer in the thirty-fifth minute. Afterward, DC United gained massive possession for the remainder of the encounter, however, it took until the eighty-first minute to score the winning goal. Christos defense apparently did well to hold on the stalemate and seemed to be stretching the encounter for extra-time until they eventually “succumbed” to the pressures of United.

Substitute Lloyd Dam placed home a shot past Christos goalie Phil Saunders to put the home team ahead. Ian Harkes and Julian Buescher added “insurance” goals in the last minutes to end the "Cinderella" run of the amateur club.