Tottenham defender Cameron Carter-Vickers has withdrawn from United States' under-23 squad for the upcoming Olympic qualifying playoff against Colombia.
The two-legged tie will decide which team competes in Rio de Janeiro next summer, but the U.S. will be without Carter-Vickers for both Friday's first leg in Barranquilla and next Tuesday's return game in Frisco, Texas.
Sources have told ESPN FC that the 18-year-old is unlikely to feature again this season due to a persistent back problem but is expected to be fit for the start of preseason.
Carter-Vickers and Tottenham teammate Nabil Bentaleb -- who picked up an injury in last week's under-21 match against Leicester City -- will both have their problems assessed by the club this week, but it is expected that neither will play any further part this term.
Carter-Vickers is yet to make his senior debut for Tottenham but he has regularly been included in the first-team squad since Jan Vertonghen suffered a knee injury in January, and he was on the bench for both legs of the Europa League round-of-16 defeat to Borussia Dortmund.
Earlier this year, Spurs head coach Mauricio Pochettino named Carter-Vickers as the next academy player who could graduate to the first team, telling a news conference: "We have another youngster from the academy -- Cameron Carter-Vickers.
"He is still young but has enough quality and he is training with us from the beginning of the season and playing for the U21s. It's a good opportunity to stay with us now more consistently. I think we have enough players to cover [Vertonghen's] injury."
Carter-Vickers, who was born in England to an American father and English mother, joined Tottenham's academy in 2009.
He started all five matches in the U.S.'s successful run to the quarterfinals at last summer's Under-20 World Cup, and all five games for the U.S. U23s at the CONCACAF Olympic Qualifying tournament last year.