Llanelli Scarlets and Ulster fought themselves to a standstill in a draw that was unsatisfying for both sides.
Scarlets: (5) 12:
Tries: John (2)
Cons: C Evans
Ulster: (12) 12:
Tries: Bowe, Maxwell
Ulster were seeking a bonus-point win to clinch the Celtic League, while the Scarlets wanted to give new Wales coach Gareth Jenkins the perfect send-off.
First-half tries from wings Tommy Bowe and Andrew Maxwell seemingly put Ulster on their way to the title.
But the home side dug deep, prop Phil John scoring two tries as the game ended in stalemate.
Jenkins was not the only person waving farewell to Llanelli.
Coach Nigel Davies, full-back Lee Byrne and lock Chris Wyatt were all making their last appearances.
The elements were not in Ulster's favour when the game got under way, with a sodden pitch and slippy ball making the hunt for four tries a tricky undertaking.
Understandably, the backs did not see much of the ball in the opening minutes, as the opposing packs ripped into each other with gusto.
Tackles were big, contact was bruising, with a few stray fists and feet thrown in for good measure.
Yet all the action was taking place in the Scarlets' half of the field, and on 19 minutes the pressure finally told when Ulster scored their first try.
A chip over the top of the Welsh defence was controlled by Bowe with a touch worthy of a Premiership footballer.
The wing took control of the flying ball with the instep of his boot before gathering and plunging over the line.
A second try soon followed as Andrew Trimble seized a loose ball and broke upfield, leaving Maxwell a clear path under the posts.
Fly-half David Humphreys' conversion gave Ulster a healthy 12-0 lead, with two of the required four tries already under their belts.
But the Irish dominance was interrupted by a suspected broken ankle to Ulster skipper Simon Best while Humphreys needed stitches in a gashed eyebrow.
Scarlets prop John then plunged over from close range to reduce the deficit after the home side finally worked their way into the Ulster 22.
John struck again soon after the restart from an incredible rolling maul reminiscent of the famous Pontypool pack in their 1970s pomp.
The Scarlets took a lineout just inside their own half and then wrestled, mauled and controlled their way to the Ulster tryline.
Rookie Carmarthen fly-half Craig Evans added the conversion to bring the scores level at 12-12.
The Scarlets should have had another mauled try on 66 minutes, but referee Graeme Hannah allowed himself to get run over by the Welsh surge and was unable to see the score to award it.
A swirling wind was making kicking difficult, with both Evans and Humphreys wide with efforts that would have clinched the win as the clock ticked down.
Humphreys, so often the drop-kick master, was particularly wasteful as three snap efforts sailed wide.
Ulster must now pick up at least three points at the Ospreys next week to lift the title, while rivals Leinster need to win well at Edinburgh and hope Ulster lose.
The Scarlets players, meanwhile, must wait to see who takes over from Jenkins.
Former Llanelli and Wales skipper Phil Davies is widely expected to be unveiled next week.
Scarlets wing Mark Jones:
"We would have loved to have sent Gareth off with a big win at home for him.
"Unfortunately it was a draw but Ulster were desperate to get the win to take the title and we were desperate to send Gareth away a happy man.
"It looked like two teams that were afraid to lose the game in the end, both teams defended fantastically well and it wasn't to be for either team."
Ulster coach Mark McCall:
"I'm extremely proud of the efforts of my players, it was a tough, tough match out there played in difficult conditions.
"Having got the lead we had, the Scarlets came at us really strongly at the start of the second half and we struggled to get our hands on the ball.
"But the title is very much in our hands - we need a victory next week to secure the title and for us to come here and not be beaten was a great effort."
Scarlets: Lee Byrne; Mark Jones, Matthew J Watkins, Regan King, Garan Evans; Craig Evans, Dwayne Peel; Phil John, Aled Gravelle, Craig Dunlea, Vernon Cooper (capt), Hottie Louw, Inoke Afeaki, Dafydd Jones, Jonathan Mills.
Replacements: John Davies, Matthew Rees for Gravelle (50), Chris Wyatt for Louw (40), Jonathan Edwards, Lee Williams, Gareth Bowen, Gavin Evans for Byrne (59).
Ulster: B Cunningham; T Bowe, A Trimble, P Wallace, A Maxwell; D Humphreys, I Boss; B Young, R Best, S Best (capt), J Harrison, M McCullough, N Best, S Ferris, R Wilson.
Replacements: N Brady, J Fitzpatrick for S Best (30), R Caldwell, N McMillan for Ferris (45), K Campbell, J Bell for Humphreys (36-41), T Howe.
Referee: Graeme Hannah (SRU).