Holbeach United claimed pole position in the title race thanks to Charley Sanders’ stoppage-time winner.
The second-half substitute struck at the end of Saturday’s game at Carter’s Park to send the Tigers into top spot on goal difference.
George Zuerner’s early effort had been cancelled out when Daniel Forbes levelled for Harborough Town with only eight minutes remaining.
Assistant manager Darren Edey took charge for the first time during a five-match stadium ban for boss Seb Hayes.
Edey said: “We would have taken three points before the game and it’s a nice bonus to be on top of the table.
“Nothing is won in February but everyone has to chase us down now,
The first half was probably the best we have played for a long time - if not all season.Darren Edey
“We’ve still got at least one game in hand over our rivals apart from Wisbech Town.
“It’s a good position so we’ll see what happens next.
“The first half was probably the best we have played for a long time - if not all season.
“Once again we missed chances before we scored and another couple after the goal.
“We felt relaxed and chilled at half-time but we had to make sure we did the same again.
“But in the second half, we didn’t match them for work-rate and effort.
“When they equalised late on, I thought they had the momentum to win it.
“As soon as they scored, though, we stepped it up again.
“We definitely deserved to win looking at the first-half performance.
“However, we didn’t work hard enough in the second period. We sat too deep and gave them too much space.”