Arsenal's two-point lead at the top evaporated at Villa Park after Arsene Wenger's side, not for the first time this season, failed to make their superiority count.
Arsenal had most of the first-half possession but were made to wait until the second half to get the breakthrough, when Swedish midfielder Freddie Ljungberg tucked the ball home.
But Villa soon hit back and their pressure was rewarded with Arsenal midfielder Kolo Toure's sliced clearance into his own net in the 71st minute.
Leeds moved further away from the danger zone with three points secured by a hat-trick from Australian striker Mark Viduka and an irrepressible Alan Smith, who set up five of the goals.
Harry Kewell tapped home his deft cross at the far post after 12 minutes, Irish defender Ian Harte converted a penalty after he was felled by Richard Rufus and Viduka made it three with a low cross-shot after being fed by Smith on the break.
Jason Euell converted a penalty for Charlton just before halftime. But Viduka drove home his second after Smith's run and pass and then brought up his hat-trick with another penalty after Smith had been tripped in the area.
Kewell added the sixth with a superb solo goal after picking up the ball in midfield.
West Brom were already destined for a swift return to the first division before Gary Megson's side clocked up a sixth defeat on the trot, despite their battling performance.
Malcolm Christie fired Middlesbrough ahead after 36 minutes and Boro continued to create scoring chances until Jonathan Greening fired home the second in the 76th minute.
Slovakian substitute Szilard Nemeth rounded off the win with a well-taken goal in the 87th minute.
West Ham's battle against relegation suddenly looks a lot less likely to end in victory after their rivals for the drop - Bolton and Leeds - both won and the Londoners could only scramble a late point.
Chris Marsden crossed for James Beattie to put Saints ahead a minute before halftime with his 22nd goal of the season.
West Ham fought for an equaliser and nearly had one early in the second half when Lee Bowyer sent in a free-kick, Joe Cole mis-cued his shot and Trevor Sinclair's drive was well saved by Southampton goalkeeper Antti Niemi.
But Jermain Defoe made no mistake in the 83rd minute to score a precious equaliser.
Substitute Carlton Cole came on to score Chelsea's 85th minute winner and keep his side firmly in the race for a place in the Champions League qualifiers.
Sunderland opened the scoring when Sean Thornton chested down a clearance and smacked a great volley beyond Chelsea's Italian keeper Carlo Cudicini.
Gianfranco Zola volleyed an equaliser, his 15th of the season, to make it all square after a Cole cross. A minute later Chelsea's Dutch striker Jimmy Floyd Hasselbaink had the ball in the back of the Sunderland net - only to have his effort disallowed for handball.
But Cole popped to bag the late winner after a Hasselbaink cross.
On-loan goalkeeper Andy Marriott had a nightmare debut for Birmingham as he rolled the ball out to make a clearance unaware that Robbie Keane was loitering with intent behind him - the Irish striker nicking the ball and rolling it into an empty net after seven minutes.
Paul Devlin levelled for City in the 77th minute from the penalty spot but midfielder Gus Poyet blasted a superb winner for Spurs with just two minutes to go.