The top-of-the-table showdown was settled by a clinical finish and a series of saves.
Having missed out on a chance to move level on points with the league leaders, Spalding United were left wondering how they had lost.
The answer came down to the display of Polish keeper Mateusz Zaniewski.
He protected Shaw Lane’s advantage as they went clear in the title race thanks to an early goal by Gary Burnett.
He found space through the heart of the home defence and coolly slotted past loan signing Richard Walton who conceded for the first time in 198 minutes.
Zaniewski had already denied Nathan Stainfield and Lee Beeson while left-back Adam Jackson’s shot bounced off the crossbar.
Stainfield nodded wide from Beeson’s free-kick in a positive opening.
But moments later, Shaw Lane went ahead and it took a half-time team talk to get the Tulips back to how they had started the big game.
Before the break, Nathan Whitehead nodded straight at Zaniewski and top scorer Bradley Wells fired too high.
The second period was much better by Spalding as they dominated.
However much they tried, the Tulips couldn’t find a way past Zaniewski.
Even when the keeper was beaten, skipper Ryan Qualter found himself in the right place to hook away Jordan Lemon’s header from Wells’ left-wing cross.
Neal Spafford needed to be aware at the other end with a clearance inside the six-yard box from Stevie Istead’s shot after a poor punch by Walton.
Otherwise, though, all the action saw Spalding pushing forward in search of a goal.
Inevitably, Matt Varley’s long throws produced some opportunities and claims for fouls inside the penalty box.
Wells’ header was tipped wide by Zaniewski following a flick from Stainfield.
Soon afterwards, Beeson flashed a shot wide but the Tulips couldn’t create more clear-cut chances until right at the end of a game which had plenty of effort without too much quality.
Whitehead’s long-range curler was pushed away by Zaniewski.
Stoppage-time started as Beeson delivered the corner kick and Stainfield’s header was tipped over the bar.
Shaw Lane managed the final moments for what may prove to be a key result.
If they go on to become champions, the Ducks will look back at days like this.
It was a case of ‘job done’ with a fifth successive away win – all coming with clean sheets.
The Barnsley-based side have dropped just two points since their only league defeat so far this season.
However, they must be thankful to Zaniewski as the Tulips’ unbeaten run ended.
4-4-2: Walton 6; Walker 7, Spafford 7, Stainfield 7, Jackson 7; Lemon 7 (sub Lockie 74 mins), Whitehead 7, Varley 7 (sub Wightwick 81 mins), Beeson 7; Wells 7, Barraclough 6. Subs not used: Field, Fleming, Duggan.
4-1-3-2: Zaniewski; Austin, Kelvin Lugsden, Qualter, Radford; Istead; Byrne (sub Wafula 81 mins), Harris, Kieran Lugsden; Allott, Burnett (sub Brewster 90 mins). Subs not used: Tuohy, Purkiss.
Burnett (18 mins, 0-1).
Istead, Wells, Harris (fouls); Kieran Lugsden (time-wasting).
Nathan Whitehead – another hard-working display in central midfield.
Rugby Town (A) – Saturday.