Celtic League/Cardiff Blues 20 Ulster 17:Ulster saw their Magners Celtic League aspirations ended in the most dramatic of climaxes as Nick Macleod kicked an injury-time winner for Cardifff at the Arms Park last night.

Tries in the second half from Roger Wilson and Andrew Trimble opened a 17-10 lead and looked to have stolen a precious win against their fellow title contenders.

Yet with just three minutes of normal time remaining, Cardiff engineered a stunning comeback that left Ulster on their knees as replacement Tom Shanklin burst over to level the scores before Macleod slotted over with his third attempt to settle the game.

A crucial decision went Cardiff's way as Ulster were judged to have got a hand to his second attempt, which rolled behind the dead-ball line, handing the Blues a scrum five yards out from which the young outhalf clinched it.

It was agonising for Ulster, who remain four points behind Leinster having played a game extra, though the writing has been on the wall with their recent poor form that continued last night when they played the first 40 minutes in shackles.

The tone for the half was set as Paul Steinmetz and Cardiff's Ben Blair scuffed their opening shots at goal, though Ulster's centre slotted over his second attempt on his team's first visit into Blues territory on 12 minutes.

Whether it was the absence of David Humphreys or not , Ulster struggled to gain a foothold and spent much of the first half firefighting. The back row particularly struggled, but Ulster's defence, aided by Cardiff's generosity, could not be faulted.

Tommy Bowe, Bryn Cunningham and Wallace all provided timely interventions to plug gaps in the white dam under wave after wave of attack from the Blues.

Their task became harder when Andrew Trimble was possibly harshly treated with a yellow card for a high tackle on Blair, who dusted himself off to kick the equalising penalty.

Ulster survived the 10 minutes without conceding further, though it was only a matter of time before Cardiff finally made the most of an opportunity. Macleod skipped through and his scything run released Chris Czekaj, who kept his legs pumping under the weight of two tacklers to step over the line.

Blair's conversion handed the Blues a 10-3 lead at the break.

Ulster were handed another let-off as Rhys Williams spilled the ball a yard from the try line, and that near miss galvanised the Irish.

Ryan Caldwell led the charge until Wilson shrugged off two tacklers to cross on 62 minutes following a sustained period of pressure.

When Steinmetz and Trimble combined to make the most of Cardiff's mix-up in midfield seven minutes from time, the game looked to have taken a decisive turn.

But Ulster could not hang on as the home side pressed forward and the arrival of Shanklin to the fray helped Cardiff snatch back the initiative in thrilling fashion.

CARDIFF BLUES: B Blair; R Williams, J Robinson, M Stcherbina, C Czekaj; N Macleod, M Phillips; G Jenkins, R Thomas, T Filise; B Davies, R Sidoli; A Powell, X Rush, M Williams. Replacements: G Powell for Filise (63 minutes), D Jones for Davies (64 minutes), T Shanklin for Stcherbina (66 mins).

ULSTER: B Cunningham; T Bowe, A Trimble, P Steinmetz; A Maxwell; P Wallace, I Boss; B Young, R Best, S Best (capt); J Harrison, R Caldwell; S Ferris, R Wilson, N Best. Replacements: K Campbell for Boss (64 mins), T Barker for Caldwell (79 mins).

Referee: David Rose (RFU).