Ricardo Pepi scored seconds after coming into the game as the United States beat El Salvador 1-0 at Orlando's Exploria Stadium on Monday night to win Group D and clinch its spot in the CONCACAF Nations League finals in June.
The U.S., fresh off a 7-1 shellacking of Grenada, started a strong XI, with interim manager Anthony Hudson knowing all his team needed was a win or draw to advance to the Nations League semis.
The hosts never found an opener in a scoreless first half despite applying plenty of pressure, and had a pair of injury scares with both goalkeeper Matt Turner and midfielder Yunus Musah requiring attention from the team's medical staff.
Giovanni Reyna, making his second start for the U.S. after a World Cup in which he found minutes hard to come by, hit the post as play resumed after the break and veteran Tim Ream had a close-range volley blocked away seconds later.
Pepi came on for Daryl Dike on the hour mark and made an instant impact, latching onto a Weston McKennie through ball, holding off his defender and chipping El Salvador keeper Mario Gonzalez to give the U.S. some breathing room in a game in which it had dominated but failed to score.
Fellow substitute Taylor Booth picked out Pepi on the left side of the area in the 79th minute for a chance to double the lead, but the FC Groningen striker didn't get enough bend on his shot and the ball sailed just wide of Gonzalez's far post.
The defending champions join Mexico, which won Group A on Sunday with a 2-2 draw against Jamaica, in the four-team Nations League finals from June 15 to 18 at Allegiant Stadium, the home of the NFL's Las Vegas Raiders. The last two spots will be decided on Tuesday when CNL group-stage play concludes.