Munster, slipping to their first loss in eight competitive games this season, paid the price for fielding a largely second string line-up.

Munster coach Tony McGahan retained just three of the players who started last Sunday's European cup victory at Sale Sharks, resting star names like Paul O'Connell, Ronan O'Gara and John Hayes.

Ulster also tweaked the side that lost last time out to Harlequins - Ed O'Donoghue and the fit-again Stephen Ferris were recalled at the expense of Carlo Del Fava and Matt McCullough.

Winners over Edinburgh in their most recent league game, Ulster edged into Munster territory off the kick-off and missed a second-minute penalty when Niall O'Connor shot wide of the uprights.

A hip injury brought the young out-half's evening to a premature end, yet Ulster had an able replacement in Ian Humphreys, the younger brother of the province's legendary number 10 David Humphreys.

Predictably, Munster lacked cohesion in the early stages with a new half-back partnership and a much-changed pack.

Nonetheless, Paul Warwick booted them into a sixth-minute lead when he landed a penalty from distance.

As the sides continued to feel each other out, Ulster's Ryan Caldwell and David Pollock were prominent, with the latter charging into the visitors' 22 on a powerful run.

The men in white looked the hungrier in contact situations and a swift counter involving Darren Cave and Pollock had Munster scrum half Peter Stringer scrambling to clear.

Humphreys succeeded in levelling the game at 3-3, with a crisp 22nd-minute penalty hit, and Ulster got over for their opening try four minutes later.

The Munster defence fell asleep as Andrew Trimble wrestled back control of possession and a lovely pop pass from Paddy Wallace sent Timoci Nagusa spearing through a gap.

It was a move straight off the training ground and the Fijian's angled run saw him scoot past Denis Hurley and go over by the posts.

Humphreys tapped over the conversion for 10-3 but Matt Williams' men were brought down to earth off the restart when lock Ryan Caldwell was sin-binned for taking Hurley out as the Munster full-back chased his chip kick.

Warwick thumped the resulting penalty kick through the posts and Munster were very much in the game, albeit playing well below par.

Ulster continued to create chances as the first half wore on. Wallace, after combining with Nagusa, was sprung into space down the right and was unfortunate not to nab a try in the corner.

The Ireland international did really well to break, kick ahead and gather and he managed to ground the ball despite being turned head over heels by Lifeimi Mafi.

However, television match official John Carvill ruled that Wallace, hit by two last-ditch tackles, had been bundled into touch before he dotted down.

The 14 men of Ulster regrouped and made no mistake in the 32nd minute when Nagusa was sent charging over in the left corner, showing a clean pair of heels to Warwick and Stringer and shipping Hurley's tackle close to the line.

Humphreys missed the conversion from wide out and it was Munster's turn to bounce back.

They countered after Ulster had lost possession in midfield, kicking ahead and Anthony Horgan was only just denied by Bryn Cunningham as the Munster winger stretched to ground the ball.

With his team 15-6 in arrears at half-time, McGahan had stern words for Mick O'Driscoll and his players and much more was expected from Munster in the second half.

As it was though, Ulster continued to look the side more likely to score.

The visitors were getting little change at scrum and lineout time and Humphreys missed a chance to extend Ulster's lead from a long range penalty.

The European champions introduced James Coughlan, Mike Prendergast and Jeremy Manning into the fray in a bid to freshen things up but there was no moving Ulster.

Munster could not get within a sniff of the hosts' try line during a fragmented second period, and it was left to replacement scrum half Isaac Boss to end the barren spell.

Boss scored on the hour mark as he sniped forward off the back of a scrum, getting away from Prendergast and Alan Quinlan before he slipped by Horgan and crashed over the line.

Humphreys' clipped conversion raised the flags for a 22-6 score-line and a deflated and strangely subdued Munster had no response.

Mafi and Manning tried to launch counter attacks from their 22 but forward passes and Ulster's first-up tackling suffocated the life of the leaders.

Ulster had a late chance to squeeze in a bonus point try but after a brilliant half-break from Cave, Trimble was crowded out in the left corner.

Speaking afterwards, Ulster boss Matt Williams said: "Obviously there were some great players missing from that Munster side but I know to beat Munster any day you have to be playing well.

"I think we just really needed to win that a lot more. We've played a lot of good rugby without the results.

"We were much more disciplined (tonight), apart from the sin-binning which I thought was silly from us.

"Our biggest plus tonight was our defence which I thought was superb. To keep Munster tryless, not many other teams can do that."