Leeds (14) 27 Tries: Buderus, Hall, McGuire, Donald Goals: Sinfield 5 Drop Goal: Sinfield
Sinfield's drop-goal proved the difference between the teams
Points machine Pat Richards missed a last-gasp penalty as Leeds hung on to win a play-off thriller and move to within one win of another Grand Final.
After Richards gave Wigan hope with his 30th try of the season, followed by a penalty to tie it up at 26-26, Leeds' Kevin Sinfield slotted a drop-goal.
Leeds then infringed as Wigan tried to run from their own line but Richards missed for the third time on the night.
And Wigan, 12-0 up inside six minutes, were left to rue too many mistakes.
A second last-gasp win over Wigan (Leeds had also put them out of the Challenge Cup with a last-minute try at Headingley in May) booked the reigning Super League champions their place in the semis in a fortnight's time.
But Wigan now face a knock-out game at home to Hull KR on Friday night.
It also means that St Helens now have the right to choose their semi-final opponents, while sending Huddersfield to Warrington next Saturday for the other elimination semi - and a repeat of last year's Challenge Cup final.
Leeds, already minus Jamie Jones-Buchanan, were also without Lee Smith, which meant Keith Senior returning to the centre, while Ian Kirke came in to the pack, Chris Clarkson coming in to make the bench.
And the visitors were further disrupted when they found themselves 12-0 down inside the first six minutes.
Sam Tomkins was first to react when Martin Gleeson timed his jump right to claw back a Paul Deacon bomb.
And, after skipper Sinfield uncharacteristically kicked out on the full from the re-start to give the Warriors another perfect attacking position, the Wigan full-back then claimed a virtuoso second try when he weaved his way through from 20 yards out.
Super League's top points scorer Richards improved both before adding a 16th-minute penalty to stretch Wigan's lead to 14-0. But the contest did not take long to turn back Leeds' way.
First, Wigan lost the influential Deacon, who aggravated a groin injury after falling awkwardly in a tackle on Danny McGuire.
Then, after giving away a silly penalty, Greg Eastwood slipped in Danny Buderus, on the ground where he broke his leg last season, for his first try in three months.
And, just two minutes later, Leeds were in again as McGuire's presence in the contest suddenly heightened.
The half-back lofted a looping pass out wide on the right, Richards gambled at leaping for an attempted interception, but failed, leaving Hall waiting behind him to cash in.
Richards was then denied a chance to get Wigan back on course by a stunning try-saving tackle in the left corner by McGuire, who was not finished yet.
His stray elbow on Joel Tomkins angered the Wigan forward into another show of indiscipline at the play-the-ball when he tried to kick out of the Leeds man's hands - and Sinfield had the chance to level it at 14-14.
If that hurt Wigan, it was nothing to how McGuire left them feeling when Leeds stole ahead for the first time minutes into the second half.
Good handling by Sinfield and Brent Webb set up McGuire, who steamed through a gap.
But Wigan responded within four minutes when Liam Farrell threaded his way in, Richards adding the extras to leave again at 20-20.
Leeds were back in front on 61 minutes when the soon-to-depart Scott Donald sneaked in at the left corner for his 10th try of the season.
But again, just three minutes later, Wigan responded through Richards, who also went over in at the left corner before missing with the conversion.
Richards then missed again with a penalty but it was third time lucky when he slotted another attempt to tie the scores at 26-26.
The Wigan joy was shortlived when, with five minutes to go, Sinfield stroked over his drop goal.
Then came the last-minute drama when, with Wigan on the burst down the left flank, McGuire took out George Carmont just as Donald was doing the same to Richards.
After a length delay from the officials, merely adding to the tension, the verdict was a touchline penalty on the 40-metre line - but Richards pulled it short and left to leave Leeds euphoric.
Victory could come at a cost for Leeds, McGuire leaving the field on a stretcher with knee ligament damage following that last-minute tangle with Carmont.
Wigan coach Michael Maguire said: "It was painful. It was really tough to take. We've a group in there who are very disappointed.
"It could have gone either way. You can't always write the script you want. We need to re-group.
"I don't want to focus on what happened at the end. It's about what we did for the whole 80 minutes. We had opportunities but unfortunately didn't take them.
"Paul Deacon has strained his groin quite badly. It's not looking great at the moment."
Leeds coach Brian McClennan said: "We didn't get out of the blocks well. They were playing some good footie.
"But I thought the team showed a lot of fortitude and composure with the way we fought back. We didn't look at the scoreboard, we just concentrated on putting some plays on.
"I thought Greg Eastwood was very strong, creating breaks down the middle, and our little guys jumped on everything. It was a good game to watch."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.