Pro12: Ulster 28-17 Scarlets
ULSTER (18) 28
- Bowe, Diack, Court
- Pienaar 2
- Pienaar 3
SCARLETS (3) 17
- G Davies, S Timani
- Williams 2
Ulster's first-half display set up a largely comfortable victory over a battling Scarlets outfit in the opening Pro12 semi-final at Ravenhill.
Tries from Tommy Bowe and Robbie Diack helped Ulster lead 18-3 at the break although Bowe's score came after an apparent trip on Aled Davies.
Tom Court's score put the game beyond the Scarlets' reach before scores from Gareth Davies and Sione Timani.
Ulster will face either Leinster or Glasgow in the final on 25 May.
The Scarlets suffered a blow before the start as fly-half Rhys Priestland was forced out after suffering a recurrence of the Achilles injury which ruled him out of the Six Nations.
Priestland's replacement Owen Williams kicked the Scarlets into a fifth-minute lead but Ulster were quickly on terms as Pienaar slotted a penalty after Alain Rolland had penalised Johan Snyman for holding on in the tackle.
As the Scarlets showed early enterprise, Williams missed a chance to put them ahead again when he hit the post from a 35-metre penalty.
Andrew Trimble and Liam Williams were then both sin-binned after exchanging punches with the Welsh outfit being awarded the relieving penalty after Jared Payne's initial break.
The Scarlets were entitled to feel aggrieved about Ulster's opening try in the 25th minute Rolland and his officials missed a clear trip by Diack on Aled Davies in the build-up to the score.
Instead, George North was penalised moments later and after Ulster opted for the line-out, Pienaar's long pass set up Bowe to score as the home side had numbers out wide.
Pienaar's conversion extended Ulster's lead to 10-3 as one sensed that the match had turned in the home team's favour.
Ulster's decision to turn down another certain three points was vindicated in the 34th minute as Diack rumbled over after Johann Muller's fetch in the line-out from the throw of blood replacement hooker Rob Herring.
Herring was on for the outstanding Rory Best at that stage but the Ireland hooker was soon back on the pitch as he delivered a man-of-the-match display with Nick Williams also impressive for the winners.
Pienaar missed the conversion but the South African extended Ulster's lead to 18-3 by the interval as he kicked another penalty in injury-time.
The Scarlets needed to score first after the break to keep any hopes alive but instead Court's try effectively finished off the contest.
Centre Darren Cave almost got the score himself as he jinked his way towards the Scarlets line but the finishing yard was supplied by Ireland prop Court as he barged his way over, with the TV official confirming the try.
With the Scarlets already losing Scott Williams to injury in the first half, their bench options were being exhausted as hooker Ken Owens, George Earle, Aaron Shingler and Aled Davies were all forced off by knocks.
Hooker Owens had to be stretchered off after a clash of heads although he was able to sit up before being taken off the field.
The match then entered a lull after all the stoppages but Scarlets replacement scrum-half Davies ran a superb solo try in the 63rd minute after picking up possession on the Ulster 10-metre line.
Williams's conversion reduced Ulster's lead to 25-10 but Piennar quickly stretched the margin again with a penalty.
Amid a plethora of changes, Ulster's performance became ragged in the closing stages with the Scarlets, boosted by scrum domination, added a further try with replacement Timani supplying the finish.
Williams added the conversion but it was little consolation for the Scarlets.
Ulster: J Payne, A Trimble, D Cave, S Olding, T Bowe, P Jackson, R Pienaar; T Court, R Best, D Fitzpatrick, J Muller, D Tuohy, R Diack, C Henry, N Williams.
Replacements: R Herring for Best 73, R Lutton for Fitzpatrick 56, I Henderson for Tuohy 67, M McComish for Williams 68, P Marshall for Jackson 59, M Allen for Trimble 75, P Nelson for Olding 67, C Black for Court 69.
Scarlets: L Williams; G North, J Davies, S Williams, A Fenby; O Williams, A Davies; P John, K Owens, S Lee, G Earle, J Snyman, A Shingler, R McCusker (capt), J Turnbull.
Replacements: E Phillips for Owens 47, R Jones for John 59, J Adriaanse for Lee 56, J Ball for Earle 50, Si Timani for Shingler 45, G Davies for A Davies 45, A Thomas for L Williams 41, G Owen for S Williams 21.
Referee: A Rolland (IRFU)