Leinster came from 12 points down at half-time to defeat Connacht in the PRO12 clash at the RDS.
Ray Ofisa and Brian Tuohy scored tries to fire the underdogs into a deserved 20-8 at half-time lead after Devin Toner had crossed first for the hosts.
However, three penalties and a Luke Fitzgerald try put Leinster 24-20 ahead by the 65th minute.
A further Isa Nacewa penalty and Ian Madigan drop goal put further daylight between the teams late on.
With Johnny O'Connor hurtling into tackles and Niall O'Connor a steadying presence at out-half, Connacht were on course for their first away win over Leinster since September 2002.
Connacht produced all the early pressure and O'Connor duly drilled a ninth-minute penalty through the uprights.
Nacewa kicked Leinster level after Connacht prop Dylan Rogers had been sent to the sin-bin for cynical play after hampering Cillian Willis at the back of a ruck but another O'Connor penalty put the visitors ahead again.
A surging run from Nacewa got Leinster back on the attack and with Connacht caught flatfooted, Toner powered onto a pass from Willis and barged past final defender Matthew Jarvis for a 20th-minute try.
However, Connacht took control in the second quarter and a long, inviting pass from Niall O'Connor put Ofisa ghosting inside David Kearney for a try which the creator converted.
Tuohy's try stretched Connacht's advantage to 12 minutes and he had gathered Henry Fa'afili's pass and slipped past Nacewa to score to the right of the posts and O'Connor again kicked the conversion.
However, Leinster improved hugely after the break and two Nacewa penalties reduced the arrears to 20-14.
Tuohy roused Connacht with a spirited kick chase up the left wing, but he knocked on when attempting to regain possession just metres from the Leinster line.
Indiscipline from Connacht allowed Ian Madigan to send over a huge penalty as the rain started to pour.
Fitzgerald's crucial try came after replacement prop Nathan White helped Leinster win a scrum against the head with Leo Auva'a and the impressive Willis involved in the move.
Nacewa converted and added a penalty as the visitors' challenge faded and Madigan's drop goal on the stroke of full-time meant that Connacht missed out on a losing bonus point.
Leinster: I Nacewa, F Carr, E O'Malley, L Fitzgerald, D Kearney, I Madigan, C Willis, H van der Merwe, R Strauss, J Hagan, S Sykes, D Toner, K McLaughlin, R Ruddock (capt), L Auva'a.
Replacements: N White for Hagan 41, D Ryan for McLaughlin 50, D Hudson for Carr, D Browne for Sykes 64.
Not used: A Dundon, J McGrath, J Cooney, B Macken
Connacht: G Duffy (capt), M McCrea, E Griffin, H Fa'afili, B Tuohy, N O'Connor, F Murphy, B Wilkinson, A Flavin, D Rogers, M Swift, M McCarthy, J Muldoon, J O'Connor, R Ofisa.
Replacements: TJ Anderson for Ofisa 41, D McSharry for Jarvis 50, P O'Donohue for Murphy 52, R Loughney for Wilkinson 53, E Reynecke for Flavin 53, S Layden for McCrea 63, R Ah You for Rogers 66, D Gannon for McCarthy 74