Two dramatic late tries sealed a thrilling victory for Melton in this top-of-the-table clash and extended their lead to six points in Midlands 2 East (South).
It was a heartbreaking finale for a spirited Market Harborough side which had started the match in second spot just three points adrift of their visitors.
And they looked to be on their way to victory deep into the second half after grinding out a 15-13 advantage with Melton hampered by having two players sin-binned during the half.
But Melton showed their title credentials with that late two-score blast - the second being a penalty try - to turn the contest on its head.
A big crowd enjoyed the battle of the championship contenders at Northampton Road, with the visitors’ bigger pack dominating the scrum from the start.
That strong platform helped Melton maintain early pressure and they went ahead with a try following a driving maul, skipper Marcus Badham touching down for the first of his hat-trick of tries.
Harborough were getting very little possession and struggled to gain any sort of foothold in the game.
But they took control just after the half-hour mark with two tries in a three-minute spell.
The first came from Jack Johnston, who caught an overthrown lineout ball on the five-metre line and touched down.
Then Ed Parker ran 70 metres, chipping the ball over the last defender along the way, to score a second try against the run of play and out Harborough into an unlikely 10-5 lead, neither of the scores being converted.
But Melton were immediately back on the offensive and they levelled matters by going over for a second time from a driving maul. Dan Wakefield leapt high at a lineout and Badham went over.
The teams kicked off the second period locked at 10-10 and Melton picked up where they left off, putting the Harborough try line under sustained pressure.
Less than a minute after the restart Matt Cox kicked a penalty to re-take the lead.
Undaunted, Harborough made incursions into Melton territory with Ed Sumpter being brought down short of the line but stretching out to touch down and make the score 15-13 to the hosts.
Melton then had Badham yellowed-carded for a transgression and Harborough must have started to believe they could topple the leaders with skipper Joe Caunt leading from the front.
The home side went for the kill but, after a series of penalties five metres from the line, they could not find a way through to the try line.
And then Melton showed why they are the league leaders with those two tries in the last five minutes.
The first came from an extraordinary move when almost the entire Melton team joined in a maul and set up Badham to touch down.
The final score was a penalty try awarded after Harborough conceded a string of penalties, Matt Cox converting to win a valuable bonus point.
Melton are next in action on Saturday (2.15pm) when they host struggling Vipers, who have won just once in the league this season.
Harborough, who have slipped to third behind Lutterworth, have another tough game at the weekend against fourth placed Oadby Wyggs.
Other league results from Saturday: Belgrave 25 Peterborough 24; Biggleswade 18 Olney 23; Leicester Forest 22 Oakham 19; Lutterworth 22 Oadby Wyggestonians 11; Vipers 27 Rushden & Higham 27.