Seattle Sounders endured their first defeat in this season's CONCACAF Champions League when Herediano completed a smash and grab job in Washington on Tuesday night.
Yosimar Arias' 25th minute free-kick produced a surprise 1-0 result as the Costa Rican recorded their first points in four Group D matches to give themselves some hope of qualifying for the next phase.
Before the meeting, the Sounders had won three from three in the competition to hold a commanding lead in their group which still stands at three points after Mexican club Monterrey were victorious with a 3-1 home win over Guatemala's Comunicaciones.
Sigi Schmid was forced to deploy a weaker-than-usual Sounders outfit due to injuries and a cluttered fixture list but he did not blame that for the subpar performance.
"Obviously, we're dealing with some injuries and a heavy schedule, so we have to make some lineup decisions based upon that," said Schmid.
"But at the end of the day, our quality tonight wasn't good enough."