Munster's makeshift line-up upset the odds in a match that was supposed to be about how many tries Ulster could score.

The visitors simply torched the script and came back to snatch a dramatic win at Ravenhill which appears to have done fatal damage to Ulster's Magners League challenge.

Ulster's intent had been to top the table outright overnight, ahead of Leinster's game with Connacht on Saturday, but their losing bonus point puts them on equal points with Michael Cheika's side and is bound to leave Ulster deeply wounded after losing control of a game they confidently led 21-3 at half-time.

Instead of pushing on to secure the bonus point, Ulster's game and defensive shape fell apart as the going got fast and loose in the second half.

A brave Munster effort, with Jerry Flannery, John O'Sullivan and skipper Alan Quinlan had immense games, seeing the visitors score three tries to come away with a fully deserved win ahead of their Heineken Cup quarter-final at Llanelli next week.

Ulster ignored a kickable penalty attempt, which could have drawn the game in the dying minutes, to go for a try but Munster's excellent defence held firm.

The momentum never returned to the home side's game and Ulster failed to score any points from the 24th minute onwards.

The winning score came courtesy of former rugby league star and new signing Brian Carney who marked his debut by rubbing plentiful salt into what had become a shambolic Ulster performance.

Ulster had made their intentions clear from early on with tries being top of their agenda.

Tommy Bowe came close to scoring in the seventh minute and only a great covering tackle from Christian Cullen prevented the home side from getting out of the traps early.

But Ulster were not to be denied and a minute after Cullen's heroics, Andrew Trimble found Paul Steinmetz on a cutback run off the left wing and the Kiwi burst through to score under the posts and give David Humphreys a straightforward two-pointer.

The visitors' cause was further damaged by the sinbinning of prop Tony Buckley after a fracas with Justin Harrison from the restart and Ulster used the 10 minutes well by producing a score from Roger Wilson, again converted off the upright by Humphreys, to give them a 14-0 lead after 20 minutes.

With Munster restored to their full complement, Eoghan Hickey managed their first points from a penalty but the home side immediately struck back when, from a scrum, Humphreys put Trimble clear though referee Allain Rolland failed to notice a blatant forward pass from Ulster's outside half.

With Humphreys adding his third conversion Ulster now led 21-3 and looked odds on to secure a bonus point.

Seven minutes before the break, they nearly got their score with Trimble only hauled down by a last ditch tackle from Ian Dowling and then Rory Best crossed the line but the try was disallowed due to obstruction and Ulster had to be content with their 21-3 lead at the break.

But that was as good as it got for Ulster. Five minutes after the restart, John O'Sullivan's gut-busting break from his own 22 set up a try for Trevor Halstead and with Hickey's conversion Munster - missing virtually their entire first-choice side - had closed Ulster's lead to 21-10.

Three minutes after the hour, the crucial score arrived after Paddy Wallace carried the ball over his line under pressure from the advancing red hordes.

O'Sullivan picked up from the five metre scrum and substitute outside half Jeremy Manning converted his score.

Munster were right back in it and only trailed by four points.

With Humphreys retiring hurt, Ulster never regained their shape, though in truth their forward effort had already imploded.

Five minutes from time, after some fantastic ball retention, Carney scored off Alan Quinlan's cross kick and Manning converted.

Ulster (21) 21.
Tries: Steinmetz, Wilson, Trimble. Cons: Humphreys 3.

Munster (3) 24.
Tries: Halstead, O'Sullivan, Carney. Cons: Hickey, Manning 2.
Pens: Hickey.

Att: 12,000