|Connacht (7) 7|
|Try: Marmion Con: MacGinty|
|Leinster (0) 6|
|Pens: Madigan 2|
Connacht increased their lead over Leinster at the top of the Pro12 to four points by grinding out a one-point win over their interprovincial rivals.
A Kieran Marmion try, converted by AJ MacGinty, gave the hosts a 7-0 lead at half-time at the Sportsground.
Leinster replied with two Ian Madigan penalties after the interval but were unable to breach the Connacht line despite exerting late pressure.
Both sides remain well-placed to make the semi-final play-offs.
The hosts had won their last six matches in all competitions - five of those with maximum points - but they were made to battle all the way in an intense clash where defences dominated.
The Leinstermen had won all three games against fellow Irish provinces this season and lost just once to Connacht in their last six, but rode their luck as their hosts threw wave after wave of attack at them in an intense opening 10 minutes.
Connacht enjoy strong first-half wind advantage
With a strong wind in their favour, Connacht were camped inside the Leinster 22, but Luke McGrath forced an important turnover before Dominic Ryan made four huge hits in defence.
Pat Lam's men had to cope with the early loss of Nathan White to injury, but it did not seem to hamper them as they brought on Ireland international Finlay Bealham for his 50th appearance, and finally forced the game's opening score after 13 minutes.
Scrum-half Marmion made the breakthrough, chasing down a perfect chip from winger Niyi Adeolokun to touch down, with fly-half MacGinty adding the extras.
The number 10 continued to build the pressure, pinging a kick from his own 10m line deep into Leinster territory, but Luke Fitzgerald - making his 150th appearance for the boys in blue - soon forced another brilliant turnover.
Madigan slots over two Leinster penalties
Madigan hit back straight after the interval for Leinster, slotting his first kick at goal perfectly from the right-hand side after a brilliant counter ruck saw Connacht penalised for not rolling away.
MacGinty's break 10 minutes later led to Leinster being penalised for a high tackle on Adeolokun, but Connacht did not trouble the scorers again as they kicked to the corner only for Ryan to steal the lineout.
As the game passed the hour mark, the score was still locked at 7-3, but a Leinster scrum soon saw an offside Marmion penalised, and Madigan's kick brought his side to within a point.
Leinster brought on their big guns in search of a winning score, with Mike Ross, Devin Toner, and Jamie Heaslip all off the bench. And the latter almost made an immediate impact as he stole the ball and tore up the pitch.
But the visitors were held up over the line with two minutes remaining and, as the clock wound down, Connacht forced the turnover to end a thrilling contest.
Connacht: T O'Halloran; N Adeolokun, B Aki, P Robb, M Healy; AJ MacGinty, K Marmion; D Buckley, T McCartney, N White; Q Roux , A Muldowney; S O'Brien, J Heenan, J Muldoon (capt)
Replacements: D Heffernan, R Loughney, F Bealham, A Browne, E McKeon, C Blade, S O'Leary, R Henshaw.
Leinster: I Nacewa (capt); F McFadden, G Ringrose, B Te'o, L Fitzgerald; I Madigan, L McGrath; C Healy, R Strauss, T Furlong; R Molony, H Triggs; D Ryan, J van der Flier, R Ruddock
Replacements: S Cronin, J McGrath, M Ross, D Toner, J Heaslip, E Reddan, N Reid, Z Kirchner