The Edinburgh reverse also condemned them to fourth place among the Welsh regions in the final Magners League standings and Amlin Challenge Cup rugby next season in Europe.
But despite those twin disappointments Luke Charteris' team will still have a massive say in who goes into the Magners League Play-Offs. Mighty Munster may be untouchable at the top, and guaranteed a home semi-final - and a home Grand Final if they can maintain their unbeaten home record this season - but there are still a number of mathematical variables below them.
Second placed Leinster's win in Aironi at the weekend kept them on course for a home semi-final. A win in their final game, against Glasgow Warriors at the RDS, will be enough to put them into the Play-Offs, but they can be beaten into second place, and the other home semi-final, by the Blues.
Paul Tito's men still have it all to do in their final two games, classic Welsh derbies against the Dragons and Play-Off outsiders the Scarlets, but two bonus point wins, could see them reach 70 points - the highest total that Leinster can reach with a bonus point win over Glasgow.
If the two teams end up on 70 points then it will be their points difference that will come into play. Leinster currently lead in that category by nine points and then have a massive 13 try advantage in tries scored.
But it is not only second placed Leinster and fourth placed Cardiff Blues who can go into the final throes of the regular season dreaming of a home semi-final. Third placed Ulster are still in the hunt, although they need Glasgow to win in Dublin and the Blues to lose at least one of their final two games to earn the luxury of a home game at Ravenhill.
Ulster's final fixture is also at Rodney Parade, where they haven't won since the 2006/07 season, and is bound to be a testing experience for Rory Best's men as they seek to add a Magners League Play-Off place to their Heineken Cup quarter-final appearance this season.
Ronan O'Gara's last second penalty against the Ospreys may have condemned the reigning champions to a 22-20 defeat at the Liberty Stadium at the weekend to push them out of the Play-Off places, but they still have a chance of making the semi-finals.
If the Dragons and Scarlets beat the Blues, and the champions win their final game in Italy against Aironi, then they will make the grade. A Scarlets win over the Blues on the final Friday could also see them creep into the Play-Off reckoning if the Blues and Ospreys fail to pick up any more wins or, in the case of the Blues, points.
It promises to be a fascinating final Friday in the regular league season on 6 May with five sides still harbouring hopes of home draws and Play-Off places - and another team, the Dragons, with the power to be dream makers or breakers.
Magners LeagueS STANDINGS
P W D L PF PA Diff TF Pts
1 Munster 21 18 0 3 474 321 153 41 79
2 Leinster 21 14 1 6 457 333 124 46 65
3 Ulster 21 14 1 6 460 405 55 41 63
4 Blues 20 13 1 6 441 326 115 33 60
5 Ospreys 21 11 1 9 541 408 133 56 59
6 Scarlets 21 11 1 9 465 430 35 45 57
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