Tamworth 0-2 Dartford
Dartford striker Danny Harris scored one and set up a second to help secure victory against Tamworth at The Lamb.
The Darts broke the deadlock when Harris cut in from the left flank to fire the ball past Tamworth goalkeeper Cameron Belford from 20 yards.
The visitors continued to push forward, going two up when Kenny Clark nodded home a Harris cross from close range.
The Lambs threw everything at their opponents in the closing stages of the second period but Dartford stood firm.
This was only the third defeat that the Lambs have endured in 12 home games since Dale Belford took over as manager in January - and the first two were at the hands of last season's Conference champions Mansfield Town and Cambridge United, this season's early pacesetters.
VIEW FROM THE DRESSING ROOM
Tamworth manager Dale Belford:
"To come out of the Bank holiday weekend with no points is very disappointing.
"We possibly deserved something at Hereford on Saturday, but this was our worst performance since I took over in January.
"If you've got aspirations of staying in this league, you've got to be beating, or at least not losing to, the likes of Dartford."