London Wasps are in danger of missing out on next season's Heineken Cup after falling to a 19-14 defeat to Saracens in Sunday's Guinness Premiership derby at Vicarage Road.
The league champions dominated the second half and appeared to have snatched victory when Gloucester-bound winger Tom Voyce crossed with three minutes to go.
But Francisco Leonelli struck as the match entered injury time to effectively end Wasps' chances of finishing in the play-offs.
More worryingly for Ian McGeechan's side, they must produce a spectacular late run in their last four remaining games to book their place in next season's European Cup.
England fly-half Danny Cipriani missed three of his six shots at goal in an otherwise lively display but opposite number Glen Jackson was virtually flawless in finishing with 14 points.
It was a dire spectacle that provided little entertainment for the 16,257 sell-out crowd that had turned out to watch the London derby at Vicarage Road.
Jackson and Cipriani swapped penalties in a nervy opening lit-up by a sharp break by Cipriani who was eventually halted by full-back Chris Wyles.
Strong runs from Chris Jack and Cencus Johnston put Saracens back onto the front foot but slow ball prevented them from capitalising.
Jackson slotted a second penalty to reward their early superiority and hen it was time for the home side to show their defensive mettle with centre Brad Barritt smashing James Haskell back 10 yards.
A long-range three points from Cipriani levelled the score but Saracens went back on the offensive with Barritt breaking through the midfield.
Former All Black scrum-half Justin Marshall continued the move before being bundled into touch by three tacklers.
Showing impressive acceleration, Cipriani took a quick 22 and found acres of space but once again Wasps turned over possession.
The champions, well on top in the possession stakes, continued to look dangerous in attack with Dominic Waldouck almost squeezing in at the corner.
Only a superb late tackle from Jackson kept him out and the Kiwi went on to land two further penalties to give Saracens a 12-6 interval lead.
Wasps set about reeling in their opponents with gusto once the second half began with Cipriani hauled down inches short of the line by Marshall.
Josh Lewsey was becoming more prominent as Wasps continued to probe away but Cipriani missed a penalty from two yards inside his own half.
Saracens' defence was coming under heavy pressure from the opposition pack and they eventually infringed and this time Cipriani made no mistake.
Scrum-half Joe Simpson carved them open once again but there was no support and the move died.
Lewsey swept Wasps into another promising position but Cipriani nudged the ensuing penalty - which was well within his range - wide.
But the visitors finally took the lead for the first time in the 78th minute.
Justin Melck turned over possession and Cipriani quickly sent the ball wide to Mark van Gisbergen who chipped ahead for Voyce to touch down in the corner.
But Saracens struck back less than two minutes later, substitute Ben Jacobs creating space and offloading at the perfect moment to give Leonelli an easy run-in.
Jackson converted and when Wasps infringed in the dyeing seconds the match was over, banging a large nail into the coffin of their Heineken Cup ambitions.
Pens: Jackson 4
For London Wasps:
Pens: Cipriani 3
Saracens: 15 Chris Wyles, 14 Francisco Leonelli, 13 Kameli Ratuvou, 12 Brad Barritt, 11 Rodd Penney, 10 Glen Jackson, 9 Justin Marshall, 8 Ben Skirving, 7 Wikus van Heerden, 6 Chris Jack, 5 Steve Borthwick (c), 4 Tom Ryder, 3 Cencus Johnston, 2 Fabio Ongaro, 1 Matias Aguero.
Replacements: 16 Alex Walker, 17 Tom Mercey, 18 Justin Melck, 19 David Seymour, 20 Mickey Wilson, 21 Gordon Ross, 22 Ben Jacobs.
London Wasps: 15 Mark Van Gisbergen, 14 Tom Voyce, 13 Dominic Waldouck, 12 Riki Flutey, 11 Josh Lewsey, 10 Danny Cipriani, 9 Joe Simpson, 8 Dan Leo, 7 Tom Rees (c), 6 James Haskell, 5 George Skivington, 4 Simon Shaw, 3 Pat Barnard, 2 Rob Webber,1 Tim Payne.
Replacements: 16 Joe Ward, 17 Charlie Beech, 18 Richard Birkett, 19 Marty Veale, 20 Mark Robinson, 21 Jeremy Staunton, 22 Lachlan Mitchell.
Referee: Andrew Small