Jordan Spence scored his first goal in Milton Keynes Dons colours on Tuesday night, but it was not enough to stop his loan club from slipping to defeat to Colchester United.
Spence's header gave the Dons hope after Craig Eastmond and Jabo Ibehre had given Colchester a two-goal lead, but Macauley Bonne's 78th minute strike killed off the visitors' hopes.
The defeat leaves the Dons 11th in Sky Bet League One, six points off the play-off places.
Meanwhile, Dan Potts made his second start for League Two side Portsmouth, but he also suffered the bitter taste of defeat as Southend United came from behind to steal the points at Fratton Park.
Andy Barcham's early effort edged Pompey in front, but goals in the last 15 minutes from Will Atkinson and Barry Corr gave Southend a 2-1 victory.