Connacht delighted a near 6,000-strong crowd at the Sportsground as they gave Heineken Cup champions Leinster a comprehensive five-try beating.
First half tries from David McSharry, Fetu'u Vainikolo and Tiernan O'Halloran fired the hosts into a 22-6 half-time lead, with debutant Dan Parks pulling the strings at out-half.
Leinster were unable to wrestle back control of the game and Eric Elwood's men secured a memorable bonus point success with closing tries from George Naoupu and Ronan Loughney.
Parks, the RaboDirect PRO12's record points scorer, was a steadying presence as Connacht faced into a buffeting wind early on.
Ian Madigan opened the scoring for Leinster five minutes in, drilling a penalty over to punish Johnny O'Connor for some sloppy ruck play.
Man-of-the-match Michael Swift was inches away from marking his record 150th league appearance with a try, Tom Sexton doing well to deny the Connacht veteran as he crashed over the try-line.
From the resulting scrum, centre McSharry cut clean through - fed by Parks - to score a fine try to the left of the posts. The former Scotland international added the extras.
Madigan replied for the visitors courtesy of a meaty penalty kick from the left, however injuries to Gordon D'Arcy (ribs), Quinn Roux (shoulder) and the returning Rob Kearney (back) left Leinster needing to adjust.
Connacht took full advantage, relishing the ferocity of the forward exchanges - O'Connor and Mike McCarthy were to the fore - and using the ball intelligently for their backs to exploit the space afforded to them by a lacklustre Leinster defence.
On one such occasion McSharry injected pace into a move and the supporting Robbie Henshaw sent Vainikolo breaking away on the left, with the Tongan winger stepping inside John Cooney's final challenge to score.
Parks clipped over the conversion from the left and as Leinster continued to struggle, a break from O'Halloran followed up by a clever Parks punt almost saw Kieran Marmion get in under the posts.
Connacht kept the pressure on and when Brendan Macken interfered with Marmion at the base of a ruck, the Leinster centre was shown a yellow card.
The remaining 10 minutes of the first half saw Leinster leak eight more points. O'Halloran scrambled over in the right corner from an Eoin Griffin pass, and with time up Parks landed a long range penalty.
Joe Schmidt sent on all-Ireland international front row of Cian Healy, Sean Cronin and Mike Ross, early in the second period, as Leinster started to play with much more directness.
Madigan missed a penalty opportunity and despite better results up front, Leinster were unable to hit back on the scoreboard.
Leo Auva'a fumbled a long, inviting pass from Madigan as one of their most promising attacks ended in a knock on.
Connacht were forced on the defensive, particularly after O'Halloran was sin-binned for not releasing a tackled player, but Leinster lacked their usual cutting edge behind the scrum.
After Henshaw went close with a drop goal effort, Leinster lost Auva'a to the sin-bin and Connacht seized their opportunity again - a lineout maul provided the platform for number 8 Naoupu to plunge over.
That unconverted fourth try was followed by a final seven-pointer, replacement prop Loughney showing his alertness at a late lineout to touch down and replacement Miah Nikora converted to put 28 points between the provinces.
A final missed try-scoring opportunity proved it just was not Leinster's night. In injury-time, Healy had a foot in touch before he managed to muscle his way over in the left corner.
David McSharry, Connacht's first try scorer, tries to break away from Ian Madigan and Devin Toner during Friday's interprovincial derby in Galway