|Super League elimination final|
|Leeds Rhinos (14) 20|
|Tries: Ablett, Watkins, Jones-Buchanan Goals: Sinfield 3, Hardaker|
|Catalan Dragons (6) 24|
|Tries: Williams 2, Taia, Anderson Goals: Bosc 4|
Sam Williams snatched a dramatic late try as Catalan Dragons earned their first win at Headingley to end Leeds' hopes of a league and cup double.
Carl Ablett went over for the Rhinos before Williams grabbed his first try.
A converted Kallum Watkins try and Zak Hardaker's penalty put the Challenge Cup holders 14-6 up at the break.
Tries from Zeb Taia and Louis Anderson had Dragons ahead, only for Jamie Jones-Buchanan to cross for Leeds before Williams sealed it.
He pounced on a handling error by Rhinos winger Tom Briscoe to fall over the line in the last minute.
Victory sets up a preliminary semi-final at Huddersfield on Friday after the Giants were forced into an elimination play-off match following their 57-4 loss at Wigan.
Meanwhile, defeat ended a disappointing Super League campaign for Leeds, who have failed to win in a league game since July.
Their recent form has been in stark contrast to their Challenge Cup-winning exploits at Wembley last month, when they lifted the trophy for the 12th time after a 23-10 final win over Castleford.
Despite the recent slump, play-off specialists Leeds went ahead on 15 minutes with Danny McGuire finding Ablett, who charged over.
Kevin Sinfield added the extras but the Rhinos soon found themselves pinned back as Hardaker and forward Mitch Achurch came up with some desperate defending to keep Catalans at bay.
While Williams was denied once, the former St George Illawarra Dragons half-back linked up with captain Gregor Mounis to go over for his first score.
|Leeds Rhinos' Super League slump|
|1 Aug: L 20-14 v Bradford Bulls (H)|
|17 Aug: L 40-36 v London Broncos (A)|
|29 Aug: L 13-12 v St Helens (H)|
|5 Sep: L 29-6 v Wigan Warriors (A)|
|12 Sep: L 24-19 v Hull FC (A)|
|20 Sep: L 24-20 v Catalan Dragons (H)|
Catalans were hampered by their own poor discipline, conceding five penalties to one inside the first half-hour before centre Vincent Duport was placed on report for a late tackle on Sinfield.
While the Leeds captain failed to shake off the hit to kick the penalty, Hardaker teed up the two points.
Watkins showed some great ball control with his feet to twice kick ahead to himself and score after Morgan Escare conceded possession with a knock on.
Dragons second-rower Taia jumped above Briscoe to collect a high kick from Thomas Bosc and score before Anderson powered on to a Williams pass and bumped off Hardaker to touch down and put the French side ahead for the fist time with more than 20 minutes remaining.
Escare went close for Catalans before the Rhinos took the lead when Jones-Buchanan was put through by Sinfield, but it was only a momentary advantage as Williams was gifted a late winner by Tom Briscoe's handling mistake.
Catalan Dragons coach Laurent Frayssinous:
"We made history by becoming the first Catalan team to win at Leeds.
"In the context of the play-offs, against a team that has so much experience, to win that type of game it is pretty special.
"We needed luck at the end when Tom Briscoe dropped the ball and Sam picked it up to score, but the performance, especially defensively, has been awesome and the attitude of the boys was good."
Leeds Rhinos coach Brian McDermott:
"We weren't good enough at any period of that game to win it.
"I didn't think Catalans were great either but they were dogged throughout and exploited a couple of defensive weaknesses.
"They scored the try off Tom's error but that's not where the game was lost at all. We had at least another two defensive blunders and mediocre attack."
Leeds Rhinos: Hardaker; Briscoe, Watkins, Moon, Hall; McGuire, Sinfield; Leuluai, Burrow, Peacock, Jones-Buchanan, Ablett, Delaney.
Replacements: Aiton, Bailey, Achurch, Sutcliffe.
Catalan Dragons: Escare; Oldfield, Pomeroy, Duport, Millard; Bosc, Williams; Elima, Henderson, Anderson, Taia, Whitehead, Mounis.
Replacements: Lima, Pelissier, Bousquet, Garcia.
Referee: Phil Bentham (RFL)