Southend United suffered a disappointing 2-1 away defeat to bottom club Northampton Town at Sixfields Stadium on Tuesday night.
Mathias Kouo-Doumbe opened the scoring with a powerful header inside the opening ten minutes, before Michael Timlin got his second of the season soon after to level for Blues.
Chris Hackett restored the host’s lead just over ten minutes into the second-half, and that was enough to condemn Blues to defeat.
The loss extended Blues’ run without a win to seven in League 2, ahead of the visit of Wycombe Wanderers on Saturday.
Three changes were made from the draw at York City on Saturday, two of which were enforced. Cian Bolger and Adam Thompson missed out through injury, while Kevan Hurst dropped down to the bench.
In their place came Mark Phillips, Marc Laird and Lee Barnard, with Blues switching to the 3-5-2 formation, with Phillips partnered by John White and Ben Coker in the back three.
Blues were still trying to settle with the new set-up when they fell behind. Kouo-Doumbe rose highest from Chris Hackett’s corner to put the hosts ahead.
The early goal seemed to have rattled Blues, but they responded almost immediately through Timlin.
Laird, making his first start since Torquay away in December, played in Timlin who calmly slotted past Matt Duke.
Laird then had a chance himself after meeting Ryan Leonard’s cross, but he couldn’t keep his cushioned volley down.
Northampton should’ve retaken the lead in the 35th minute, from another set piece.
Zander Diamond headed into Ricky Ravenhill’s pass, but the midfielder could only blaze over the bar.
Moments later, and Blues had a great chance of their own. Anthony Straker played in Corr, but the striker’s shot lacked conviction and was easily saved by Duke.
The second-half lacked the same tempo, and Brown made a reasonably early change as Freddy Eastwood came on for Lee Barnard.
But almost immediately, the Cobblers restored their lead. Emile Sinclair beat Phillips for pace and teed up Hackett, who slotted past Dan Bentley.
Hackett thought he had made it 3-1 minutes later, but he was adjudged offside as he headed past Bentley.
The introduction of Kevan Hurst and Jason Williams gave Blues some initiative, but they were unable to find a second equaliser.
They will be looking to put that right against Wycombe Wanderers on Saturday.
Blues: Bentley; Leonard, White, Phillips, Coker; Atkinson, Timlin, Laird (Hurst 72), Straker (Williams 82); Corr, Barnard (Eastwood 56).
Subs: Smith, Payne, Banton, Gomis.
Attendance: 3,846 (377 away fans).