Gyasi Zardes netted an 86th-minute winner to send the United States into their 13th Gold Cup final after a 1-0 semi-final triumph over Qatar in Austin on Thursday.
It could have been an entirely different story but Hassan Al Heidos missed a 61st-minute penalty for the Asian champions.
US head coach Gregg Berhalter brought on Zardes along with Nicolas Gioacchini in the second half to devastating effect, with the pair combining for the winner.
Gioacchini burst into the box and beat a man, before a side-foot pass which found Zardes to hammer home from close range.
US will play either Mexico or Canada in Sunday's final, as they chase their seventh Gold Cup title.
Qatar's Hashim Ali lashed a seventh-minute chance wide, before the US were denied by goalkeeper Meshaal Barsham's double save from Schalke talent Matthew Hoppe's effort and Paul Arriola's rebound.
US keeper Matt Turner produced a stunning finger-tip save to thwart Abdulaziz Hatem's 21st-minute volley.
Barsham was alert again in the 52nd minute, getting out quickly to deny Daryl Dike's low shot.
Qatar won a penalty on the hour mark after a VAR review on James Sands' tackle but Al Heidos skied his effort over the bar.
Berhalter brought on Zardes for Dike in the 63rd minute, along with Gioacchini for Hoppe in the 81st minute, reinvigorating the US attack and the pair made the decisive contribution late.