Crystal Palace celebrate Alan Lee's first-half opener
Crystal Palace ensured their Championship survival but condemned opponents Sheffield Wednesday to League One football next season after an afternoon of incredible passion and tension ended in a draw at a sold-out Hillsborough.
The game finished with Wednesday besieging the Palace goal, but the visiting team held on to clinch the point they needed to seal their survival.
Alan Lee had put Palace in front with a thunderous header but Leon Clarke equalised close to the break with a superb strike, although the Eagles felt he should have been penalised for a foul on Danny Butterfield in the build-up.
Wednesday dominated after the interval but Ambrose struck with a composed 16-yard finish before Darren Purse stabbed home at the far post late on to ensure a grandstand finish.
Palace's celebrations are tinged with uncertainty as the south London club are in administration and facing serious questions about their survival.
Ambrose and Hart savour Palace survival
The Eagles have no funds to remain operating beyond the end of the season and face the prospect of selling off their players to generate income, while the short-term contract of manager Paul Hart has expired.
Hope rests with the CPFC 2010 consortium, which has expressed an interest in buying the club.
Wednesday chairman Lee Strafford has made it clear that relegation is not a financial disaster for his club, but it is certainly a major frustration for the Owls, who looked likely to avoid the drop after an upturn in results followed the appointment of Alan Irvine in January.
But Wednesday had won only one of their previous 11 league games going into Sunday's encounter and, despite refusing to throw in the towel after twice falling behind, they will play third-tier football next term after a largely disappointing season.
Palace should perhaps have taken the lead in the fourth minute when skipper Shaun Derry laid the ball invitingly into the path of an unmarked Calvin Andrew, but the striker's initial shot was parried by Lee Grant and his follow-up effort was blocked.
It was an early warning of the threat that the Eagles possessed and Grant was in action again midway through the half to palm clear a well-struck free-kick from Ambrose.
But there was nothing the Owls keeper could do to prevent Lee from putting the visiting side in front with a powerful header from six yards when the striker rose unchallenged to meet Ambrose's corner after 24 minutes.
During an enthralling and competitive opening half, the heavily involved Grant had been kicked in the head by a very high foot from Andrew as the striker stretched to reach a looping ball, while James O'Connor sustained a cut above his eye as he competed for a loose ball.
But until Clarke's equaliser shortly before the interval there was little sign that Wednesday's endeavours would lead to a goal for the home side.
Jermaine Johnson was a lively presence on the right flank and forced a decent save from the excellent Julian Speroni, who also held a weak Mark Beevers header and a poor Luke Varney strike.
Wednesday had failed in a penalty appeal after Clarke went down under a challenge from Patrick McCarthy but they were perhaps fortunate that referee Mike Dean allowed play to continue in the build-up to the Owls equaliser.
Clarke tussled with Butterfield wide on the left as they competed for the ball, with the Palace defender going to ground.
But Dean saw no infringement, and Clarke raced into the box before brilliantly curling his right-foot strike beyond the despairing dive of Speroni.
The goalscorer's joy was short-lived, as he sustained a dislocated toe kicking the advertising hoardings in celebration and had to be stretchered from the field in just about the last significant action of an opening half that ended with Dean followed off the field by several frustrated Palace players.
The Owls went on the offensive after the restart, with Butterfield making an excellent header to cut out a cross from O'Connor. Marcus Tudgay had a shot blocked from the subsequent corner as Palace struggled to clear their lines.
Darren Potter became the second Wednesday midfielder to sustain a cut after an aerial challenge with Derry and Wednesday, who had O'Connor off the field when Palace scored, were again temporarily down to 10 men.
It did not damage their growing momentum and it took another scrambled clearance to prevent the home team from taking the lead while Johnson, who tangled with Ambrose as the tension started to show, went close with a hooked volley.
Irvine 'sad' for Owls fans after relegation
Speroni then denied Varney with an excellent save after the Wednesday forward shrugged off two Palace defenders before shooting from across goal.
But the crucial third goal went to Palace, with Sean Scannell superbly picking out a completely unmarked Ambrose 16 yards from goal.
Ambrose opted to shoot first time and his precise side-footed effort eluded Grant's despairing dive and sparked huge celebrations in the away end.
The goal was tough on the home team, who would have levelled almost instantly but for a superb block by McCarthy, who smothered a shot from Owls substitute - and former Palace player - Tom Soares.
Substitute Francis Jeffers failed to connect with a cross but Purse did convert a flick-on after 87 minutes to ensure a gripping finish.
Stern John should have put Palace ahead for a third time after a two-versus-one break but his strike hit the inside of the post and was cleared off the line.
There were five minutes of injury-time but the Eagles closed out the game and the final whistle saw a pitch invasion.
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