Knowing they just needed a draw to advance, the visitors' plan was evident not long after the opening whistle, often putting 10 or 11 players behind the ball, even though a goal would have forced RSL to score at least three times.
Despite Herediano's defensive outlook, the home side had plenty of looks at goal, putting eight shots on frame throughout the 90 minutes. However, goalkeeper Leonel Moreira, a veteran of Costa Rica's 2011 Copa América team, was equal to every single effort.
Moreira also had the crossbar to thank, though, as RSL's Fabián Espíndola squandered the best chance of the game in just the sixth minute. In one-on-one, the Argentine pushed it past the keeper, he fired a slightly off-balance shot high of the goal, nicking the crossbar despite having the net at his mercy.
In the 16th minute, Nat Borchers appeared to put RSL on top as he headed home a corner kick, but a foul was called on Chris Schuler before the ball even reached Borchers.
Herediano almost made RSL's task incredibly tougher in the 25th minute as they had a header from a corner kick cleared off the line by Luis Gil.
Moreira again earned his keep when he parried away a header from Borchers bound for the top-left corner of the net in the 28th minute. He finished the opening stanza with seven saves, including another excellent save on a blast from Gil.
Herediano almost had the goal it needed to deal RSL an all-but-fatal blow in the 46th minute, but Nick Rimando made a key save on Esteban Ramírez.
After four or five more half-chances by RSL, the Costa Ricans once again nearly put it away as Yendrick Ruiz hit the far post on his right-footed shot from just inside the right side of the penalty area.
RSL went through about a 10-minute phase after the where they struggled to get up into the attack, with Herediano's technical skills proving particularly troublesome in keeping RSL from winning the ball back.
The tension rose as time wound down, with Salvadoran referee Elmer Bonilla issuing three yellow cards in the 89th minute or later, but RSL could not find the goal they needed.
Real Salt Lake won't have much time to dwell on the loss, as they square off against Vancouver in Saturday's regular-season finale before playoffs get underway next week.