Chesterfield maintained their 11-point lead at the top with a hard-fought win over promotion rivals Port Vale.
The Spireites started brightly with Craig Davies's close-range header from Mark Allott's cross hitting the post.
There were few chances in the rest of the half but the hosts took the lead soon after the interval, Jack Lester converting Dean Morgan's fine cross.
Chesterfield secured the points when Deane Smalley sidestepped Stuart Tomlinson to slide home.
Chesterfield boss John Sheridan told BBC Radio Sheffield:
"I thought it was a very very solid performance, I thought we well deserved to win the game.
"Started the game very brightly, could have been possibly two or three goals up in the first 15 minutes and we hit the ground running against a team who I think will be in the playoffs.
"I thought we were very effective in what we wanted to do and this is how we were going to try and win it."
Port Vale caretaker manager Mark Grew told BBC Radio Stoke:
"I'm disappointed with the way the goals were conceded.
"We've told them this week that the biggest threat is from crosses into the box.
"The season's not over by any means but we're disappointed with the way we've conceded and that's something we've got to work on."