Magners League Reaction:Leinster still find themselves top of the Magners League after last night's defeat but they were second best to Connacht, who now have genuine ambitions of securing a Heineken Cup spot for the first time next season.
The Sportsground in Galway was rocking after Michael Bradley’s side defeated the European champions 27-13 to move off the foot of the table.
Connacht, who take on Toulon in the semi-final of the Amlin Challenge Cup at the end of the month, now have Ulster in their sights plus a place in next season’s Heineken Cup for the first time.
The two sides are level on 26 points after 16 games with only the top three Irish provinces in the Magners League qualifying for the Heineken Cup. Ulster host Connacht at Ravenhill in the final round of matches next month.
Leinster were looking for a win to guarantee themselves a home semi-final, especially with Brian O'Driscoll returning from a knee injury in a strong starting line-up.
But Connacht bounced back from last Sunday's defeat to Munster and rose to the occasion with captain John Muldoon and fullback Gavin Duffy both making huge contributions.
Tries from Brian Tuohy, Michael Swift and Troy Nathan helped Connacht to only their second win over Leinster since 2004.
“Our lads responded very well to the challenge. It was a very good win and I thought we were the better side from top to toe. It is a good win for us,” said Bradley on RTÉ Morning Ireland.
“We're level with Ulster but the most important thing was to bounce back from the Munster match and say to the people of Connacht that the Sportsground is a difficult place for people to come to. We've done that.”
“We have Toulon coming after the Scarlets game here (at the Sportsground). I think there should be a rush for tickets now if you get that sort of entertainment and bang for your buck.”
Leinster coach Michael Cheika put his hands up and said his side came into the game with the wrong attitude.
"Connacht have shown pretty convincingly all season that they are a good side, even in the game up in Dublin when we were lucky to win,” said Cheika after the game.
"I don't think that they're a bottom of the league team and we know that they have a lot of quality because we have coached a few of them ourselves.
"We lacked an edge in defence. We had a lot of possession but we didn't use it properly, but in the second half we attacked the line better.
"We worked hard, but it's another game that we have lost here because we lacked the correct attitude.
"Brian (O’Driscoll) finished the game and he's fine, but Girvan (Dempsey) suffered a neck injury and we just have to manage our resources now with a game coming up against Glasgow on Friday."