Dave O’Callaghan’s decisive try handed Munster a 22-20 dramatic victory over Irish rivals Ulster and booked their place in the Guinness PRO12 play-offs with two games remaining.

Heading into the Thomond Park clash lying second in the table, Munster knew victory would guarantee a top-four spot, while in-form Ulster’s own semi-final hopes were also in the balance as they were level on points with fourth-placed Scarlets.

Rory Best and Angus Lloyd traded early tries but an otherwise cagey first half saw the sides head to the dressing room locked at 10-10.

However, an enthralling second period saw the momentum swing back and forth – the lead changed hands on four occasions – before Munster eventually prevailed to preserve their record of just one loss in any competition since mid-December.

An early second-half penalty put Ulster ahead, before the impressive Keith Earls’ try made it advantage Munster, Luke Marshall then restored the visitors’ lead but O’Callaghan found the try-line late on and Tyler Bleyendaal nailed the conversion for the win.

It ends Ulster’s unbeaten Guinness PRO12 streak at seven games but Munster know haven’t lost to their interprovincial rivals in the last six encounters.

A frantic start at Thomond Park saw the sides level at 7-7 with only six minutes played. Firstly, Ulster produced an inexorable driving maul from which Best benefitted – bundling his way over.

Paddy Jackson added the conversion but the hosts were soon level as Munster skipper Peter O’Mahony made the initial burst and Lloyd darted over against the side he is on loan from, Ian Keatley nailing the extras.

An offside then gave Jackson the chance to slot a 13^th-minute penalty, which he duly did, as the visitors continued to control the territory.

That domination led to another penalty following a high tackle but Ireland fly-half Jackson missed the chance to extend the advantage, as his kick drifted wide.

Munster finally began to get a foothold in the lead up to half-time and when Ulster pulled a scrum down in their own 22, Keatley made no mistake from the tee.

Things could have got even better for Rassie Erasmus’ men before the break but Andrew Conway was held up over the line.

Ulster’s leading try-scorer this term, Jacob Stockdale, thought he had given his side the lead early in the second period when he went over the whitewash but the try was ruled out for a forward pass in the build-up.

They settled for a 52^nd-minute three-pointer for Jackson after the Munstermen were penalised at the breakdown to edge 13-10 ahead but, with an hour played, Earls got his try.

Francis Saili showed off his lightning feet in the build-up and a sweeping right to left move put the 2009 British & Irish Lion over in the corner.

Bleyendaal narrowly failed to add the conversion and Munster’s lead lasted all of three minutes – Jackson sublimely slipping in Marshall for the score and slotting the extras for a 20-15 advantage with a quarter of an hour remaining.

But Erasmus’ troops have proved time and again this year – both in the Guinness PRO12 and in Europe – that they are a force to be reckoned with, and re-took the lead on 69 minutes.

They kicked to the corner from a penalty in the Ulstermen’s 22 and steadily marched a driving maul up to the line before several phases of pressure eventually saw O’Callaghan bundle his way over.

Bleyendaal held his nerve with the conversion and some resilient late defence denied the visitors to seal Munster’s place in the play-offs.

The Guinness PRO12 Final takes place on May 27 at Aviva Stadium, Dublin.
Fans can guarantee their place by booking their tickets via www.ticketmaster.ie

Further information: www.pro12rugby.com/final