Lee Hughes scored twice on his home debut for Port Vale after the visitors saw Charlie Barnett sent off in the fourth minute for a poor challenge on Daniel Jones.
Hughes volleyed home before Darren Purse, also on his Vale Park debut, turned home a free-kick.
Hughes then secured a 3-0 win with his second goal in the 66th minute.
Gillingham still have a game in hand on Vale, and they play Wycombe on Monday.
Cheltenham moved into third place with a 2-1 triumph over Torquay.
Keith Lowe scored his fifth goal of the season for the home side before Cheltenham doubled their lead after the break through Shaun Harrad.
Rene Howe's 88th minute score for Torquay was merely a consolation goal and not enough to deny the home side maximum points.
Burton slipped out of the top three after they were reduced to 10 men and drew 1-1 against AFC Wimbledon.
Zander Diamond was sent off in the 76th minute after Michael Symes had cancelled out Wimbledon's lead, courtesy of Gary Alexander.
Rotherham climbed up the table as they beat Northampton 3-1.
Daniel Nardiello, Ben Pringle and Michael O'Connor scored for the home side before Clarke Carlisle netted a consolation goal for the Cobblers.
Morecambe eased to a comfortable 4-1 win over York on their first ever visit to Bootham Crescent.
Lewis Alessandra put Morecambe ahead before Jason Walker equalised from the penalty spot.
Kevin Ellison then put the Shrimps back in front before Jack Redshaw scored a brace in the last three minutes of the game.
Rochdale drew 1-1 with Chesterfield after Bobby Grant scored the equaliser for the home side before being sent off.
Jay O'Shea had put Chesterfield ahead in the 55th minute but Grant equalised with a 25-yard curling shot, before being shown red for a tackle on Sam Togwell.
Southend beat Oxford 1-0 thanks to substitute Ryan Leonard's 85th minute score.
Meanwhile, Fleetwood drew 2-2 against Bradford at Highbury.
Alan Goodall headed the home side into the lead in the first half before scores from Nahki Wells and Ryan Dickson saw the Bantams edge ahead.
However, the points were shared when James Hanson was adjudged to have handled the ball, with Jon Parkin levelling from the penalty spot.
Elsewhere, Exeter drew 0-0 against Aldershot while Plymouth's game against Dagenham and Redbridge was also goalless.