USA coach Mauricio Pochettino made nine changes to his starting lineup with qualification and first place already secured, and his depleted side led through Auston Trusty's third-minute strike before Arda Güler — named Man of the Match — restored parity and set up Orkun Kökçü for a second-half lead.
Sebastian Berhalter brought USA level with a rasping effort from outside the box in the 49th minute. Trusty went off injured late, leaving the USA out of substitutions and vulnerable, and Ayhan turned in from close range to complete the comeback.
Kökçü reflected on what the victory meant after a tournament in which Türkiye had otherwise struggled.
"We're not happy, but it was very important for us because we want to keep our name," he said. "We know that we have a team with a lot of quality and we wanted to show the world that we are better than this.
"For all of us, it's the first World Cup — we have to take our lessons from this experience and work hard. For the next World Cups, we hope we can achieve more success. Our people back home deserve this because they support us everywhere we go."
Pochettino was combative in his post-match press conference, visibly frustrated that the questions centred on the defeat rather than the group victory.
"The mood is like we are going home tonight and Türkiye is staying," he said. "I need to remind you and everyone that we won the group. Sorry guys, we won."
He pushed back against suggestions the result would carry psychological weight into the knockout rounds.
"Whatever I tell you, it's not going to convince you. A newspaper is going to write whatever they think. But honestly speaking — we qualified as number one and we're going to the next round."
He dismissed the idea of a historic opportunity missed: "Making history is winning the World Cup. It's not winning three matches only within the World Cup. You're thinking a little too small."
Midfielder Weston McKennie was equally unbothered.
"Türkiye were very clinical and finished their chances. The momentum will still be there for us, for sure, in the round of 32. All 26 players on this roster can step up and do the job."
Christian Pulisic came off the bench just before the hour in his return from a calf injury and performed well enough to suggest he will be fit to start against Bosnia and Herzegovina. Pochettino was encouraged.
"Yes, I'm happy — he finished well. It was a good impact when he was on the pitch."
USA face Bosnia and Herzegovina in the round of 32 on July 1 in Santa Clara.