Chelmsford City were made to pay for an early missed penalty as they slumped to a second 3-0 defeat in four days.
Having been beaten at leaders Welling United on Friday, the Clarets returned to face Dover hoping to get back on the winning trail.
And things looked good when Anthony Cook won a 16th-minute penalty, but Jamie Slabber's poor kick was easily saved by Mitchell Walker.
Former City man Ricky Modeste then turned the screw, first scoring direct from a corner and then teeing up Ben May for the second.
Danny Webb added a third for the visitors after Stuart Searle failed to deal with a cross to leave the Clarets with just a four-point cushion in the play-off places.
Chelmsford boss Glenn Pennyfather made three changes from his side's 3-0 defeat at Welling on Good Friday, with Cook, Donovan Simmonds and Max Cornhill in for Joe Whight, Kyle Vassell and Justin Miller.
Kenny Clark was able to play despite his red card on Friday, while only Whight of the three omissions was on the City bench.
The first action of the game was punctuated as a photographer took a tumble by the corner flag, and needed treatment from the Chelmsford physio.
Chelmsford made a bright start, but from the very outset it looked as though Dover would be dangerous on the break, as was proved when Moses Ademola was caught on the edge of the box, but Dover made a mess of the free-kick.
Billy Bricknell volleyed well wide from an angle, before Michael Bakare burst through but lost possession before he could pull the trigger.
But Chelmsford would soon have a golden chance after a frenetic spell in the Dover box. First David Bridges played in Donovan Simmonds and his shot was well saved by Walker, before Bridges' effort was blocked by Simmonds.
City continued to press and eventually Tyrone Sterling clumsily clattered into Cook right on the edge of the box, and referee Carl Fitch pointed at the spot – but Slabber's penalty was weak and Walker kept it out.
Dover had half a penalty shout of their own when Mark Haines' back header almost played in Ademola, but he was pressurised by Clark and Searle was able to claim.
City were without their long throw specialist Miller, but they had to deal with Lloyd Harrington's missiles into the box, and one of those caused alarm as it was allowed to bounce with Bricknell in close attendance, but Searle claimed.
But Searle was soon picking the ball out of his net when the Whites won a corner on their left. Modeste swung the ball in and it bounced in the six-yard box and past Searle into the back of the net.
Chelmsford had barely threatened since the penalty miss and were stung again as Modeste got away on the right, cut inside and crossed for May to glance a header past Searle.
Simmonds then got to the byline but opted for a deep cross towards Cook, and the chance was gone.
There was a flashpoint when Harrington went in late on Cornhill, who screamed in agony as he went down, which led to a spot of handbags. Cook, who had just been booked, was at the heart of it but escaped sanction, and eventually Modeste and Bakare were both yellow carded in what may have been a case of mistaken identity.
The free-kick was cleared but eventually fell to Mark Haines, but his long-range shot never troubled Walker.
Bridges showed great technique to rifle a half-volley goalwards in first-half stoppage time, but it went wide of Walker's goal, before the Dover keeper did very well to prevent Cook's cross from reaching Simmonds as the Clarets ended the half strongly.
The first chance of the second period fell to Simmonds, who switched flanks with Cook at the interval. Bakare laid the ball off to Simmonds on the edge of the box, and his well-struck shot was almost spilled by Walker.
It was a quiet second period, but Cook almost sparked it in to life when he struck a free-kick from 35 yards, but Walker did well to keep it out.
Bakare broke through and had a shot deflected behind and Kenny Clark was unable to direct his header goalwards as the Clarets improved.
But their hard work was undone on 66 minutes when Ademola and then Sterling kept the ball in on the left and the latter's cross was palmed by Searle to Webb, who was presented with a fairly simple chance.
That knocked the stuffing out of Chelmsford, although Bakare did get in one-on-one but was denied by Walker, and Clark's header from the resulting corner was cleared off the line.
It should have been four for the visitors when Harrington floated in a great free-kick over the defence for sub Harry Ottaway, but his unchallenged header was wide of the far post.
Simmonds headed over at the back post from a fine Jack Ainsley cross, and that began the exodus of disgruntled Chelmsford fans.
As they were making their way out, their side did have the ball in the net but the flag had gone up against Rob Edmans before he teed up Cook to net.
Edmans himself had an effort straight at Walker, but it was Dover's fans who were celebrating at the final whistle.
City: Searle, Ainsley, Palmer, Haines, Clark, Simmonds, Cook, Bridges, Slabber (Edmans 60), Cornhill (Calvo 68), Bakare. Subs: Rainford, Whight, St Louis-Hamilton.
Dover: Walker, Kamara, Wynter, Rance, Webb, Sterling, Modeste, Harrington, May, Bricknell (Ottaway 66), Ademola. Subs: Cogan, Willock, Sessegnon, Raggett.
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