The Chairboys (manager Gary Waddock pictured) were condemned to League Two thanks to their defeat and a shock 2-0 win for struggling Tranmere Rovers at home to Millwall, leaving the Lions one point behind second-placed Leeds, who blew the chance to seal automatic promotion after Richard Naylor headed into his own net two minutes from time.
Leeds went into their penultimate match of the season at The Valley one point ahead of Millwall, with the Addicks, Swindon and Huddersfield also in contention for second spot behind Norwich.
Millwall were two down at struggling Tranmere after 66 minutes, Ian Thomas-Moore scoring from the spot on the stroke of half-time before Leeds loanee Andy Robinson netted with a potentially priceless goal for both his clubs.
Billy Paynter was again among the goals for Swindon in a 3-2 victory over Brentford. The prolific striker opened the scoring in the eighth minute only for David Hunt to equalise (33). Danny Ward restored the home side's lead (45) and Paynter (58) grabbed his 28th goal of the season before Ben Strevens narrowed the gap again on the hour mark.
Huddersfield left it very late to defeat Colchester and keep their faint hopes of automatic promotion alive. Substitute Lee Novak's header in the fifth minute of injury time was the final action of the game after Simon Hackney (76) had cancelled out Theo Robinson's 17th-minute penalty.
Leeds remain in pole position, one point ahead of Millwall and Swindon, with Charlton a point further back and Huddersfield three points behind the leaders.
Southampton , seventh, lost 2-1 at lowly Gillingham but could not have made the play-offs anyway due to their 10-point deduction for going into administration late last season. Goals from Rene Howe (19) and Josh Gowling (51) put the Gills two up and David Connolly's 65th-minute response for Saints did not alter the outcome.
Wanderers knew only victory over Orient would see them hang on for another week but it was not to be as late goals from Ryan Jarvis (78) and Wycombe old boy Scott McGleish (90) sent the Chairboys back to League Two after a 2-0 reverse.
Relegation-threatened Exeter drew 1-1 at Hartlepool. Matthew Taylor headed the visitors in front in the 37th minute but Denis Behan levelled 10 minutes from time.
Champions Norwich reached the 95-point mark with a 3-0 victory at Bristol Rovers thanks to goals from Chris Martin (31), Oli Johnson (45) and Stephen Hughes (68).
There were no goals but two red cards at stadium:mk as MK Dons and Brighton drew 0-0. Diego Arismendi and Alex Rae were both dismissed for a clash in first-half stoppage-time.
Southend defeated Stockport 2-1 in the battle of the relegated sides. Jabo Ibehre put County ahead with 19 minutes to go but goals from Harry Crawford (75) and Alan McCormack (89) gave Southend the points.
Late goals from Gavin Williams (83, 90) sealed Yeovil a 3-0 win over Oldham after Gavin Tomlin had netted the first (18) while Carlisle and Walsall drew 1-1 - Jason Price (29) cancelling out Darren Byfield's second-minute opener.