Alan Connell struck with six minutes to spare to clinch a win which would have sealed promotion on the day, had Torquay been defeated at home to Southend United in a match which ended 0-0, or had Gary Alexander not equalised for Crawley in their 1-1 draw at home to AFC Wimbledon.
The defeat for Argyle leaves them requiring one more victory to be certain of avoiding a second straight relegation and an exit from the Football League, with Macclesfield also levelling late on to snatch a 2-2 draw at home to Crewe.
Northampton also have work to do in order to be mathematically certain of survival following a 3-1 defeat at home to Bradford which in turn ensured Phil Parkinson's side will remain a League Two club for another season.
Cheltenham took advantage of Crewe dropping points with a 4-1 win over Accrington which further solidifies their play-off place, more so after Oxford United and Gillingham battled to a goalless draw.
The big win of the match day came at the Memorial Ground, where Bristol Rovers thumped fellow mid-table outfit Burton Albion 7-1, featuring a hat-trick for Eliot Richards and a brace for Matt Harrold.
Elsewhere, Shrewsbury's chances of joining Swindon in the likely top three for automatic promotion were boosted by a 3-1 win over Rotherham, whose own play-off hopes now hang by a thread going into the final three games, and Dagenham made absolute sure of their own survival with a 1-1 draw with Aldershot while Morecambe and Port Vale could not be separated in their 0-0 stalemate.