Seattle Sounders FC put forth a valiant effort 0 on the night, but ultimately falling short on aggregate 0 loss in the opening leg.
Osvaldo Alonso converted a penalty kick in the 56th minute to give Seattle a glimmer of hope, but it was Lamar Neagle's strike five minutes later that put a strong sense of belief in the team as the Sounders searched for an aggregate-tying goal.
It never came, forcing Seattle out of the playoffs for yet another season.
After a dominant first-half performance from Seattle that failed to yield a goal, the Sounders continued to apply pressure with the breakthrough coming 11 minutes after the break. Referee Jair Marrufo pointed to the penalty spot after Tony Beltran pulled down Michael Fucito in the box.
Alonso stepped up and converted the ensuing kick, hammering his shot down the middle and underneath Real Salt Lake goalkeeper Nick Rimando.
The goal helped Seattle turn the corner, as it struck again just five minutes later.
Real Salt Lake's central defense pairing of Chris Wingert and Chris Schuler, who were replacing the injured Jamison Olave and Nat Borchers, looked quite shaky throughout the match, but it was not until the 61st minute that they were exploited in open play.
Neagle, a first-half substitute, tracked down a through ball played into the box by Fredy Montero. The midfielder calmly slotted a low shot to Rimando's far post and into the side-netting.
The CenturyLink Field crowd came alive and created a "12th Man" atmosphere in an attempt to rally the Sounders.
But despite controlling play for the remainder of the match, Seattle was unable to conjure another goal to complete the miraculous comeback.
Not only does the result put Seattle out of the season, but it also marks the end to an illustrious career for goalkeeper Kasey Keller, who decided to retire at season's end.
Real Salt Lake moves on to the Western Conference Final, still awaiting the result of the other semifinal before its opponent is known.
With Real Salt Lake positioned as the third seed in the West, it would host New York if the Red Bulls advance. Otherwise, it will head to The Home Depot Center to face the Galaxy on Sunday.