Colchester now look most vulnerable to a late surge in Coca-Cola League One play-offs as they blew a golden opportunity to take three points at home to second-bottom Wycombe.
Ian Henderson set the home side on their way but veteran Gareth Ainsworth equalised in injury time.
Bristol Rovers may have left their own play-off push too late but they moved up to eighth place after winning an extraordinary seven-goal thriller against Southend, who stay rooted in the drop zone as a result.
Scott Vernon and Scott Spencer gave the visitors a shock 2-0 lead inside two minutes before Rovers struck back to lead 3-2. After Vernon's equaliser, Rovers claimed the points through an injury-time own goal from Anthony Grant.
The biggest beneficiaries at the bottom were Exeter, who started the day third from bottom but jumped four places after a 2-1 win over Walsall. Matt Taylor and a Ryan Harley penalty set the Grecians on their way.
But Tranmere plunged into the bottom four after a dismal 3-0 defeat at mid-table Brighton. Rovers had Andy Robinson sent off on their debut and fell to goals from Glenn Murray, Andrew Crofts and Ashley Barnes.
Milton Keynes Dons suffered another blow to their flickering play-off hopes as they twice lost a lead to draw 2-2 at Gillingham.
Lewis Grabban scored the only goal of the game as Brentford edged Leyton Orient in the London derby at Griffin Park.
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