The Welsh region staged a stunning fight-back to draw against French championship leaders Stade Francais at Liberty Stadium, wiping out a 13-point deficit to lead during the final throes of an intriguing pool three clash.
But Stade substitute Lionel Beauxis booted a 50-metre penalty in the fifth minute of injury-time, meaning the Parisians require a bonus-point victory against Italian minnows Calvisano on Saturday for a prized last-eight place.
The Ospreys, meanwhile, visit English champions Sale Sharks next weekend, when a bonus-point success could still be enough to clinch one of two best runners-up spots in the knockout stages.
Although television footage suggested Ospreys flanker Steve Tandy had been penalised for offside by English referee Chris White during yesterday’s late penalty incident, number eight Jones admitted he was guilty of a hand in the ruck.
Jones said: “It was me who gave away the penalty.
“I didn’t think he (Beauxis) would make it from that range, but he did, and I had to say sorry in the dressing room afterwards.
“Stade are seasoned performers in the Heineken Cup, and they did a real job on us in the first half, but we regrouped in the second period.
“We are pretty disappointed — we didn’t deserve to win the way we played in the first half.”
Stade led 19-6 after 60 minutes through a Juan Martin Hernandez try, 11 points from fly-half David Skrela and a Beauxis penalty, before Ospreys stirred and went ahead after James Hook kicked five penalties and converted wing Nikki Walker’s touchdown.
Stade were left breathing a huge collective sigh of relief after securing a share of the spoils from a game they looked to have wrapped up with only 20 minutes remaining.
Scrum-half Agustin Pichot said: “We were very close to throwing the game away.
“When you think you have won, you can sometimes lose your grip and let it go, and we made some mistakes. For many of us at Stade Francais, this season is probably our last chance of winning the Heineken Cup, and that is what our goal is.”
Tries: Walker. Cons: Hook. Pens: Hook 5.
Tries: Martin Hernandez. Cons: Skrela. Pens: Skrela 2, Beauxis 2. Drop Goals: Skrela.
Byrne, Walker, A Bishop, Henson, S Williams, Hook, Marshall, D Jones, B Williams, A Jones, Cockbain, A Jones, Tiatia, Tandy, R Jones, Lloyd.
Terblanche for Byrne (38), Spice for Marshall (77), James for D Jones (77), Lloyd for Tiatia (3), Powell for Lloyd (52).
Martin Hernandez, Saubade, Messina, Liebenberg, Dominici, Skrela, Pichot, Roncero, Blin, Marconnet, Auradou, du Plooy, Burban, Rabadan, Parisse.
M Bergamasco for Messina (55), Beauxis for Skrela (45), Szarzewski for Blin (59), M James for Auradou (70), Martin for Burban (65).
Chris White (RFU).