Pinchbeck United restored a 10-point advantage by taking their unbeaten record to 18 games.
The Knights moved further in front of their rivals thanks to goals from Aaron Eyett (2), Ollie Maltby and Liam Ogden.
Player-manager Ian Dunn said: “It took us half an hour to break the deadlock but at 0-0 we needed that first goal to settle us down.
“We had the better chances in the first half without being great in possession.
“Once we got ahead, it didn’t look like the result would go any other way.
“We asked them to up the ante in the second half by taking care of the ball in the final third.
“Considering the condition of the pitch and that we’ve been labelled a direct side, I thought we played some fantastic stuff in the second half and caused Melton all sorts of problems.
“We had more chances so it was pretty comfortable.”
Second-placed Raunds Town were beaten at Olney Town to put Pinchbeck’s lead into double figures again.
Dunn added: “We knew it would be tough for Raunds so we felt we could make that gap even bigger.
Considering the condition of the pitch and that we’ve been labelled a direct side, I thought we played some fantastic stuff in the second half and caused Melton all sorts of problems.Ian Dunn
“Looking at the table, it could be Harrowby United who get closest to us because they have games in hand and we have to play them twice.
“It’s difficult for us not to think about the title but if we keep winning, it makes everything easier. One point away to Rushden & Higham United next weekend would not be a bad result either.”
Meanwhile, Luke Gardner is due to make his comeback from injury in a friendly on Wednesday night at Parson Drove.