Andrew Tutte and Bobby Grant helped Rochdale end 10-man Gillingham's unbeaten League Two record this season with a 2-1 victory at Priestfield.
The leaders headed into the game having won their last four but were behind after 15 minutes when Tutte collected a short corner on the left and his inswinging cross evaded everyone and nestled in the far corner.
Gills encountered a further setback in the 33rd minute when Danny Jackman was shown a straight red card for lunging in on Tutte, and it got worse after the break when Grant slotted home a second.
Danny Kedwell got the 10 men back in contention with a 74th-minute penalty, but they could not find an equaliser.
The result allowed second-placed Port Vale to close to within three points of the leaders with a 1-0 success over fellow high-flyers Bradford at Valley Parade,
The winner came against the run of play in the 37th minute when Vale's leading scorer Tom Pope intercepted a headed back-pass from Bantams skipper Gary Jones, beating goalkeeper Jon McLaughlin with a left-footed shot from just inside the penalty area to end the hosts' perfect home record.
Fleetwood and Accrington moved within five points of the Gills thanks to 2-1 wins over 10-man Barnet and at AFC Wimbledon, respectively.
Barnet keeper Graham Stack saw red as his side gave up an early lead, David Ball's penalty and Tom Barkhuizen's 78th-minute winner turning things around after Jake Hyde had bundled in an early opener.
Peter Murphy and Padraig Amond were the men on target for Stanley, with Luke Moore's stoppage-time effort scant consolation for Wimbledon as Simon Bassey slipped to his first defeat as their caretaker manager.
Elsewhere in League Two, Matty Blair and Jason Walker struck early in the second half to end York's four-match winless streak with a 2-0 victory at Aldershot.
Dagenham & Redbridge clinched their first win of the campaign in emphatic style - 3-0 at home to second-bottom Wycombe thanks to goals from Dwight Gayle, Michael Spillane (penalty) and Billy Bingham.
Skipper Kelvin Langmead scored at both ends as Northampton fought out a thrilling 3-3 draw at Burton.
Tommy Wright maintained his unbeaten run as Chesterfield caretaker boss as his side drew 1-1 with Torquay at the Proact Stadium.
Bristol Rovers picked up their first victory of the season with a 2-1 win at Exeter, Rotherham were 3-1 winners against Oxford and Plymouth's clash with Southend ended 1-1.
