Charlton missed the opportunity to go top of the Sky Bet Championship as they were defeated 1-0 by Birmingham at The Valley.
A goal by 16-year-old full old debutant Jude Bellingham in the second half was enough to derail the south London side, who lost for the first time this season.
Charlton were already weakened before kick-off, with talisman Lyle Taylor missing after picking up a knock in the week while playing for Monserrat.
Although neither side created much in the way of chances in the opening period, the first half-chance fell to the hosts when Chris Solly fired over from just inside the box after 23 minutes.
A diving header on the half-hour mark by Tomer Hemed went wide of the post, while Jonathan Leko found space after 34 minutes but fired his effort off-target.
Birmingham started to press, and after 39 minutes Lukas Jutkiewicz forced goalkeeper Dillon Phillips to tip over the crossbar.
The visitors took the lead seven minutes after the restart when Maxime Colin squared to Kerim Mrabti, who slid the ball into the centre of the area for Bellingham to fire home.
Charlton made a change just before the hour mark when Jonny Williams replaced Erhun Oztumer.
The hosts started to press, but Birmingham still looked dangerous on the break. Colin engineered a solo run after 65 minutes and found Jutkiewicz, who once again saw Phillips nudge his shot over the woodwork.
Charlton made a second change after 71 minutes, with Sam Field making way for Chuks Aneke.
Lee Camp made his first real save a minute later when he did well to block a fierce drive by Solly.
A minute later, the Birmingham keeper was again called into action when he turned away a low drive by Conor Gallagher.
The home team made their third and final change of the afternoon after 78 minutes when Leko was replaced by Beram Kayal.
With two minutes of regulation time remaining, Hemed put the ball over the bar from five yards out after he was fed through by Aneke.
Referee Matthew Donohue allowed six minutes of injury time but caused controversy when he dismissed Charlton manager Lee Bowyer from the touchline.
Despite Phillips going up front in the dying seconds of the game, the solitary strike by Bellingham was enough for Birmingham to claim the win.
