Millwall's Under 23s were defeated 3-2 by Charlton Athletic in the Professional Development League on Monday afternoon.
Goals from Seb Drozd and Zak Lovelace put The Lions into a 2-0 half-time lead, but a double from Aaron Henry - with one penalty-kick - and a Daniel Kanu goal turned the game on its head inside the last 15 minutes.
There were just seven minutes played when Millwall took the lead in bizarre circumstances. Kyle Smith's cross was turned towards goal by Lovelace and saved by Nathan Harvey, but the stopper then spilled the ball at the feet of Drozd, who turned home.
Lovelace then shrugged off his marker to score from inside the area later in the half, but The Addicks then struck three times inside the final 15 minutes to secure the three points.
Henry converted a penalty after Jeremy Kyezu committed a foul, with the Charlton captain then scoring a free-kick three minutes later.
Kanu overturned the deficit late on to give the visitors the win.
Millwall: Wright, Smith, Tiensia, Davis, Penney, Topalloj, Drozd, Thompson, Briscoe, Lovelace, Boateng. Subs: Allen, Hammond, Garande, Babajide, Kyezu.
Scorer: Drozd 7', Lovelace 36'