Brian Deane's dramatic last-minute equaliser earned West Ham a 1-1 draw at Wigan Athletic and secured a play-off semi-final clash against Ipswich Town next week.
With rivals Crystal Palace losing at Coventry and Ipswich Town being held by Cardiff City, Neil Roberts' 34th minute opener had looked like sending Paul Jewell's men into fifth place and a play-off clash against fourth placed Hammers.
However, big Deano - on as a late substitute for Bobby Zamora - popped up in the final seconds of normal time to head in Michael Carrick's free-kick and break the hearts of the Latics followers at the JJB Stadium.
The result means that Alan Pardew and his troops will now visit Portman Road in the first leg of the play-off semi-final on Saturday, and then hopefully secure our place at the Millennium Stadium in the second leg at Upton Park three days later.
It also ensured that Hammers finished the season on a four-match unbeaten run that has produced three wins, one draw, three clean sheets, nine goals scored and just one conceded - excellent form as the club faces it's first ever participation in the traditional end-of-season mini-tournament.
Pardew had resisted the temptation to bring Tomas Repka and David Connolly back into the fold following their return from suspension, instead preferring to keep faith with the side that started last week's emphatic 4-0 win over Watford at Upton Park.
However, with Wigan in more desperate need of a winning result to keep their play-off hopes alive, it was the hosts who understandably made the brighter start, and Hammers had goalkeeper Stephen Bywater to thank for keeping the scores level early on.
Striker Nathan Ellington went close in the fifth minute when he latched on to Teale's cut-back and fired in a shot that deflected off Christian Dailly and produced a reaction shot from Bywater, while the young stopper had to be alert again two minutes later when he tipped former Hammer Jimmy Bullard's speculative volley round the post.
Wigan were presented with a glorious chance to open the lead on the quarter-hour mark, when Anton Ferdinand's weak back-pass let in Teale, but Bywater again came to the rescue by diverting the winger's attempted lob wide for a corner.
Having withstood that early pressure, Hammers gradually began to take a tighter grip on the game and might have opened the scoring against the run of play in the 28th minute, when Don Hutchison flicked on Steve Lomas' long throw, but Marlon Harewood stabbed his shot straight at Wigan goalkeeper John Filan from six yards out.
Just when it appeared that the game might be swinging in the visitors' favour, though, Wigan pounced to take the lead. A hopeful long pass down the left found Ellington, who cut inside and fired in a shot that was well-blocked by Dailly and Melville, but the ball spun out to Roberts, who hit a controlled volley past Bywater and into the bottom right hand corner from 12 yards out.
Another goal before the break would no doubt have had Hammers looking nervously over their shoulders but, as both sides went in for the half-time interval, the news that fellow play-off hopefuls Crystal Palace and Ipswich Town were both in danger of dropping beneath Paul Jewell's side - if things stayed as they were - perhaps had a slight psychological effect on the home team, who came out for the second half showing not as much urgency as they had done before the break.
The realisation that an unthinkable 4-0 defeat was now looking virtually impossible allowed Hammers to settle down and begin to make more use of their possession. However, it was clear that Pardew was determined not to end the regulation campaign with a disappointing defeat that would have halted our recent momentum, and the Hammers boss introduced a three-man strikeforce as the game entered the closing stages.
Connolly was introduced at the expense of Hutchison - and almost created an instant equaliser with a clever pass to Etherington, who crossed for Zamora to send in a low goalbound shot that was blocked by Wigan captain Jason De Vos, while Marlon Harewood should really have converted in the 68th minute when he rose to meet Christian Dailly's flick-on at the far post but saw his point-blank header cleared off the line by Nicky Eaden.
With 17 minutes remaining, Deane was introduced in place of Zamora and, with Wigan fairly safe in the knowledge that a 1-0 victory would suit them just fine, it was the visitors who were pressing forward in the closing stages.
With just 40 second of normal time left, a foul on substitute Nigel Reo-Coker some 30 yards out presented Carrick with the chance to curl in a free-kick that was met by the timely run of Deano, who expertly nodded the ball past Filan from the edge of the six-yard box.
As Wigan hearts sank and the magnificent 7,400 travelling Hammers fans celebrated a memorable end to their day in Lancashire, the play-off situation suddenly took on a whole new complexion, as Pards' former club Crystal Palace were handed a late reprieve and Ipswich jumped up a place to seal a mouth-watering local clash.
At this stage, it's now all about, hopefully, three matches that could play a huge part in the future of West Ham United. Big performances will be needed, and Alan Pardew's men can approach their date with destiny full of confidence.