The West Yorkshire club's fate will not be decided for another 11 days following their 31-24 defeat against Northampton.
If Worcester win the two-legged Championship play-off against Cornish Pirates, then Leeds will drop out of English rugby's top flight as only Warriors meet Premiership entry criteria. But should Pirates upset the odds - the second leg is at Worcester on May 18 - then Leeds will survive on a technicality and live to fight another day.
If they do make the drop, then at least Neil Back's (pictured) men bowed out by making a serious scrap of it, shocking Heineken Cup finalists Northampton through early tries from England flanker Hendre Fourie, his back-row colleague Rhys Oakley and wing Pete Wackett.
Saints, needing two points to secure a title play-off place, were at sixes and sevens at 24-3 adrift before normal service was eventually resumed through scores by skipper Phil Dowson and England wing Chris Ashton either side of a penalty try.
Fly-half Shane Geraghty kicked a penalty and two conversions, before his replacement Stephen Myler edged Northampton in front for the first time with a 53rd-minute penalty, and then added two later strikes.
Leeds had two players sin-binned and never came close to matching Saints' scrummaging power, and they spent most of the second half camped deep inside their own territory.
But despite making hard work of it, Saints sealed the fourth play-off spot, with Leeds' losing bonus not enough to finish above Newcastle - who were battered at Bath - ending in 12th place on points difference.
Leicester Tigers 32-23 London Irish
Leicester Tigers produced an astonishing final 10 minutes to steal a dramatic 32-23 victory over London Irish at Welford Road and seal top spot in the Aviva Premiership and a home semi-final against local rivals Northampton.
The Tigers came into the match knowing a win and bonus point would ensure top spot, but they made far too many basic errors, gifting London Irish winger Topsy Ojo with two intercept tries while missing countless chances of their own.
They trailed 23-13 with just 10 minutes to go before scoring four tries to record a stunning victory and leave London Irish devastated.
First, replacement winger Horacio Agulla raced over on the right after a flowing attacking move.
That lifted the team and the crowd, and three minutes later a try by impressive inside centre Anthony Allen left his side just three points adrift with Toby Flood's conversion.
And it was Tom Croft who put his side into the lead at 25-23, making amends for being put into touch after crossing the line in the first half.
It was left to Alesana Tuilagi, the Premiership's top try-scorer, to wrap up the comeback by outstripping the cover defence on the left to score his 12th try of the campaign, with Flood converting.
Bath 42-12 Newcastle
Bath did all they could to secure an improbable Aviva Premiership play-off spot by scoring four tries before half-time but eventually had to settle for fifth place and Heineken Cup qualification following a 42-12 win over Newcastle.
And it was a few agonising minutes after the final whistle that Newcastle players finally received confirmation that defeat for Leeds against Northampton meant the Falcons had escaped relegation on points difference.
Farrell, the teenage fly-half who started the season on loan at Bedford, is now 80 minutes from guiding Saracens into the Premiership Grand Final.
His performance was witnessed by England backs coach Brian Smith ahead of the forthcoming Churchill Cup, in which Farrell is sure to be involved.
Chris Robshaw crossed for a consolation try but it was too little too late for Harlequins, who finish seventh in the Premiership and miss out on automatic Heineken Cup qualification.
Conor O'Shea's men can still book their place in Europe's premier competition if they beat Stade Francais to win the Amlin Challenge Cup or if Northampton win the Heineken Cup.
Saracens were on course to finish the regular season top of the Premiership table until Leicester produced a dramatic comeback at Welford Road to beat London Irish.
In the end, Saracens had to settle for second place and they will tackle Gloucester at Vicarage Road next Sunday for a place at Twickenham.
Gloucester 68-17 Sale Sharks
Gloucester ensured their Aviva Premiership play-off spot, a trip to Saracens, with a crushing 68-17 win over Sale at Kingsholm.
The home side were slow into their stride but then the Sharks were blown away by the power of the home pack and some brilliant attacking play from Charlie Sharples and Henry Trinder.
The two of them collected five of Gloucester's 10 tries to ensure there was to be no fairytale endings to their distinguished Sale careers for Charlie Hodgson and Chris Jones.
Rory Lawson, Scott Lawson, Nicky Robinson, James Simpson-Daniel and Dave Lewis also touched down for the impressive hosts, while Nic Rouse and Neil McMillan were the try-scorers for the Sharks, with Hodgson contributing seven points.
Exeter Chiefs 21-8 Wasps
Exeter finished their season with a flourish as two second-half tries earned them a 10th Aviva Premiership win of the season to leapfrog opponents Wasps and finish eighth.
While the 21-8 win rounded off a fantastic season for the Chiefs, Wasps will be left wondering what they have to do to address their poor performances on the road in the Premiership where they have not won since beating Bath back in November.
Ignacio Mieres contributed 11 points with the boot to back up tries from Tom Johnson and Matt Jess.
Christian Wade scored Wasps' only try of the game before Dave Walder added a second-half drop-goal.