Millwall's Under 23s were defeated 3-2 by Birmingham City in the Professional Development League on Tuesday afternoon.
Arthur Penney and Jayden Davis found the net to cancel out Ryan Burke and Keke Simmonds' first-half goals in the second period, but Burke struck home a superb winner to give The Blues all three points.
Kevin Nugent was able to hand Joe Wright a start in goal on his return from injury, whilst Junior Tiensia and Sam Skeffington were absent after beginning loan spells at Sutton United and Barnet respectively.
The first chance of the game went the way of Millwall, but they were without a slice of luck as George Alexander's rebound hit the crossbar and bounced to safety after the striker charged down the goalkeeper's clearance.
Dan Moss had to undertake some last-ditch defending to prevent Adan George scoring the opening goal on nine minutes, with Sean O'Brien, Simmonds and Alex Mitchell all having further chances to score, but to no avail.
However, with 32 minutes played, Birmingham took the lead - and in some style as Burke's swerving, left-footed effort cannoned in off the far post.
Davis attempted to equalise before Wright made a big save to keep the deficit at one shortly after, but the lead was doubled with two minutes to go until the break as Simmonds struck across the box and into the net.
The Lions came out fighting in the second-half and with just four minutes played, they got themselves on the scoresheet as a fantastic delivery from O'Brien was headed home by Penney.
Then, just seconds after the hour-mark, the scores were level as a cross was met by an unmarked Davis on the edge of the six-yard box - the winger having no issues in heading home to make it 2-2.
The turnaround could have been complete just seconds later, but after Alexander was put through on goal, his shot was saved.
That moment was to prove pivotal as, with 67 minutes on the clock, Burke regained Birmingham's lead and scored his second of the afternoon by sending a rocket of a left-footed effort into the top corner from the edge of the penalty area.
Jordan Gillmore - a replacement in goal for Wright - then had to save from George as The Blues looked for a fourth, and with Davis, Abdul Abdulmalik and Penney all going close, but failing to equalise, in the latter stages, Birmingham were to claim all three points.
Next up for Millwall's Under 23s is a trip to Barnsley next Tuesday.
Millwall: Wright (Gillmore 60'), Muller, Moss, Penney, Ransom (Allen 46'), A. Mitchell, Burey, Duncan, Alexander, O'Brien (Abdulmalik 80'), Davis. Subs not used: Strachan, Walker.