Adam Cunnington scored twice as Tamworth inflicted a first home defeat of the season on Forest Green Rovers.
James Norwood had two chances for the hosts but Cunnington pounced on Tommy Wright's looping header for his 10th of the season to put Tamworth ahead.
The striker then scored from the spot after being fouled by Jamie Collins to become the league's leading goalscorer.
Collins netted a header following Magno Vieira's pass from Yan Klukowski's free kick, but Tamworth hung on for the win.
The home side twice went close to levelling a minute after closing the gap as Matt Taylor's shot was saved and Collins fired the rebound over the bar.
Substitute Vieira also had a chance with time running out but Tamworth held firm for their fifth away win of the season.
Second-placed Rovers went into the game two points behind Newport, but now find themselves five points adrift as the
leaders beat Ebbsfleet.
Tamworth, who inflicted a second straight defeat on Forest Green, remain seventh but close the gap on the play-off places to three points.
VIEWS FROM THE DRESSING ROOM
Forest Green Rovers manager Dave Hockaday told BBC Gloucestershire:
"We had two great chances to go ahead and we didn't take them. We were sloppy in the first half.
"I thought the lads were brilliant in the second half and we took the game to them.
"I've got to look at the positives and we deserved at least a draw.
"We're in a turbulent spell at the moment after two defeats but we've got to bounce back."
Forest Green Rovers 23 Russell 03 Stokes 05 Turley Booked 16 Asafu-Adjaye Booked 22 Green 11 Forbes (Koroma - 79' ) 12 Collins Booked 28 Brogan Booked (Klukowski - 46' ) 14 Taylor Booked 18 Wright (Vieira - 46' ) 20 Norwood Substitutes 02 Hodgkiss 21 Racine 08 Klukowski 07 Koroma 10 Vieira Tamworth 02 Tait 06 Marshall Booked 15 Courtney 35 Taylor 03 Kelly Booked (Till - 71' ) 04 Baldock Booked 08 Hendrie (Oji - 85' ) 11 Kerry 13 Breedon 07 Cunnington 09 Wright Booked Substitutes 31 Belford 17 Gudger 30 Oji 18 Till 28 Collins