A Tom Clifford free-kick condemned Newport County AFC to their second home defeat of the campaign against Southend United.
County were aiming to chalk up back-to-back victories against the Shrimpers after Saturday's 1-0 victory over Grimsby Town, although chances proved to be few and far between for both sides, who struggled on the Rodney Parade pitch.
But Clifford's effort 16 minutes from time took a deflection off the wall and left Nick Townsend helpless in the County goal to give Southend a shock lead in south Wales.
Josh Sheehan, Ryan Taylor and Nicky Maynard enjoyed late opportunities for the Exiles, but the visitors held out to pick up only their second away win of the season.
Manager Michael Flynn made three changes from County's victory over Grimsby Town on Saturday. Priestley Farquharson, Anthony Hartigan and Padraig Amond were all brought into the starting line-up in place of Ashley Baker, the suspended Scot Bennett and Dom Telford respectively.
The Exiles enjoyed a dominant start to the game with Luke Gambin and Josh delivering a flurry of superb balls into the box.
New arrival Maynard, who scored on his Exiles debut in a seemingly restorative victory on Saturday, met one of Gambin’s looping crosses but the ball just skimmed the striker’s head.
A long ball over the top then found Amond, who showed incredible control to turn and play in Maynard, but the forward’s effort was strongly denied by Southend’s Jason Demetriou.
Priestley Farquharson earned his first Football League start following an impressive display against the Mariners and the defender proved his worth showing great strength and attacking presence throughout.
A balanced first half presented no clear-cut chances for either side and both teams left the pitch goalless at the break.
The visitors began the second half with energy and Ashley Nathaniel-George forced Nick Townsend into making a spectacular save from close-range to keep the scoreline level.
County were tasked with defending against a determined Southend side for the majority of the second half and the Shrimpers managed to break the deadlock in the 74th minute through Clifford, as his free-kick took a deflection past Townsend.
It was a case of failing to take chances for County when a reply at the other end just minutes later welcomed an equaliser, however, Sheehan dragged his attempt just wide of the post.
And then a show of hard work in the box saw the ball fall perfectly for substitute Taylor, whose shot edged just above the crossbar.
With a minute left to play before the announcement of three additional minutes, Maynard found himself through on goal, but Mark Oxley pulled off the save of the night as the away side held out for the victory.
Newport County AFC: Nick Townsend, Ryan Haynes (Aaron Lewis 82), Mickey Demtriou, Matty Dolan (Jack Evans 27), David Longe-King, Priestly Farquharson, Anthony Hartigan (Dominic Telford 71), Josh Sheehan, Luke Gambin (Jake Scrimshaw 71), Nicky Maynard, Padraig Amond (Ryan Taylor 45).
Subs not used: Tom King, Ashley Baker.