|Ulster (13) 26|
|Tries: Henderson, Gilroy Cons: Pienaar 2 Pens: Pienaar 4|
|Leinster (10) 10|
|Try: Te'o Con: Gopperth Pen: Gopperth|
Ulster pulled off a magnificent win over holders Leinster to stay on course for a home semi-final in the Pro12.
Lock Iain Henderson and winger Craig Gilroy scored the tries for the win which effectively ends any hope Leinster had of making the play-offs.
Leinster had made a superb start with a Ben Te'o try helping them go 10-0 up in the seventh minute.
But they did not score again and Ulster went on to beat their Irish rivals for the first time in four attempts.
The result puts Ulster at the top of the table, at least overnight, and means Leinster's season is effectively over.
It had all started so well for Leinster as they pushed deep into Ulster territory and benefitted from an early penalty strike from Jimmy Gopperth.
After six minutes, things got even better for the visitors as they sought to rescue their already fragile-looking play-off hopes, when Te'o smashed through some weak tackling to score. Gopperth added the extras and Leinster were 10-0 up and looking comfortable.
Ulster needed to respond and they got over the line with Henderson. Ruan Pienaar converted his 12th-minute effort and then added a penalty shortly afterwards to tie the scores.
There then followed a moment of controversy after Henderson was tip-tackled by Sean O'Brien with referee John Lacey and the television match official opting for a yellow card for the Ireland flanker instead of the red one the home crowed were baying for.
Ulster, though, failed to score during O'Brien's absence, but did take the lead just before half-time through another Pienaar penalty.
Midway through the second half, Rob Kearney was sin-binned, giving Pienaar a 63rd-minute penalty which he duly slotted to stretch the lead to 16-10.
Three minutes later the South African nailed a monster effort from just inside Leinster's half and the home side now had a nine-point lead.
Leinster's dismal night was completed with eight minutes remaining when a huge Ulster power play off a scrum on Leinster's line ultimately saw Gilroy dance through for his 11th Pro12 try of the season.
Pienaar converted to make it 26-10 and the game ended with 14-man Ulster - replacement prop Andy Warwick had been binned - defending their line as if their lives depended on it.
Ulster: L Ludik; T Bowe, J Payne, D Cave, C Gilroy; P Jackson, R Pienaar; C Black, R Best (capt), W Herbst, D Tuohy, F Van der Merwe, I Henderson, C Henry, R Wilson.
Replacements: McCloskey for D. Cave (51), Warwick for Black (70), B. Ross for Herbst (70), Diack for Tuohy (65).
Not used: Herring, C. Ross, P. Marshall, Humphreys.
Sin bin: Warwick (78).
Leinster: R Kearney; Z Kirchner, B Te'o, G D'Arcy, L Fitzgerald; J Gopperth, I Boss; C Healy, R Strauss, M Ross, D Toner, M McCarthy, S O'Brien, D Ryan, J Heaslip (capt).
Replacements: Madigan for D'Arcy (63), Reddan for Boss (67), J. McGrath for Healy (58), Cronin for Strauss (58), Furlong for Ross (63), J. Murphy for Ryan (51).
Not used: Marshall, Fanning.
Sin bin: O'Brien (21), R. Kearney (64).
Ref: John Lacey (Ireland).