Late heartbreak for County, as the Stags sting late at Rodney Parade.
Manager Warren Feeney named the same starting XI that took to the field against Forest Green last Saturday, with defender Scot Bennett being unveiled as the captain.
The home side started the game brightly and with Marlon Jackson being set free by a well-weighted pass by Mark Randall and beat of a challenge from the Mansfield defence before slotting the ball home, only to be called back for a foul.
Mansfield took the lead when a cross from the left found striker Matt Green free inside the box and the forward was able to steer home his header from close range.
NEWPORT COUNTY AFC 0 - 1 MANSFIELD TOWN
The visitors lead was short lived as County were abe to pull the game back level when a Jack Compton free-kick from twenty-five yards rocketed into the bottom corner and the winger looked overjoyed with his effort as he celebrated in front of the Bisley.
NEWPORT COUNTY AFC 1 - 1 MANSFIELD TOWN
Compton was involved again shortly after when his whipped corner from the right almost crept inside the near post and had to be parried away by Scot Shearer in goal for the Stags.
HALF TIME: NEWPORT COUNTY 1 -1 MANSFIELD TOWN
Into the second half and the Exiles had to be alert early on in the second half when a dangerous ball inside the area fell kindly for Matt Green to hit, but Scot Bennett covered ground well to use his body to deflect the effort wide.
County had a half-chance on goal when a chipped corner to the near post by Mark Randall was met by Marlon Jackson, who changed direction well to glance a header towards goal but Shearer was able to gather the ball.
The visitors retook the lead when a Lee Collins cross from the right found Danny Rose, who was able to turn before arrowing an effort into the far corner and out of the reach of Joe Day.
NEWPORT COUNTY 1 - 2 MANSFIELD TOWN
After failing to create any real threats on goal, County again scored from a set-piece, when a whipped free-kick from the left was turned in by Joss Labadie at the far-post.
NEWPORT COUNTY AFC 2 - 2 MANSFIELD TOWN
The games looked destined to end in a draw until a Kevan Hurst long-range effort in the 93rd minute sailed into the top corner to give the Stags all three-points.
FINAL SCORE: NEWPORT COUNTY AFC 3 -2 MANSFIELD TOWN
Starting XI: Day, Barnum-Bobb, Turley, Bennett (c), Butler, Randall, Labadie, Myrie-Williams ('71), Compton, Rigg, Jackson.
Subs: Bittner, Bignot, D.Jones, Daf.Jones, Tozer, Owen-Evans
Referee: Robert Jones
Attendance: 2,790 (339 away)