Five sides remain in contention for those all-important 'home' Cup ties and of the four games remaining, Munster have a difficult run in, starting with tonight's game against a strong Ulster outfit, followed by away games against Gwent Dragon and The Borders.
The Dragons might lose ground follwing their trip to St Helen's tonight which would make them all the more determined to redress the balance when Munster visit in a weeks time.
If the situation remained as it stands at present in the league table, Munster would play Connacht in the quarter finals.
Munster are the only team undefeated at home in the Celtic League this season, their last reversal on home soil in any competition was to Edinburgh at Cork last April.
Ulster, who need a win to maintain their push for a European Cup spot, have won at Musgrave Park only once since December 1990 16-15 the last time they played in Munster on 10 October 2003.
That evening, Jeremy Staunton looked to have given his side the points when he converted his fifth penalty but in the eight minute of injury time, Adam Larkin kicked a penalty from the left hand side to snatch victory.
The Northerners have lost their last six matches in all competitions with their last win on the road being 20-19 at The Borders in early November.
This match is the sixth meeting between the two teams in the Celtic League with honours even at three wins apiece.
Should Munster fail to get a point from this game and Ospreys win in Swansea against The Dragons, then the Ospreys will be crowned Celtic League champions.
Munster. Shaun Payne; John Kelly, Mike Mullins, Rob Henderson, Anthony Horgan; Paul Burke, Frank Murphy; Frank Roche, Jerry Flannery, Gordon McIlwham; Trevor Hogan, Tom Bowman; Alan Quinlan, David Wallace, Jim Williams capt.
Replacements. James Blaney, Eugene McGovern, Tom Hayes, Stephen Keogh, Mike Prendergast, Jason Holland, Paul Devlin.
Ulster: Bryn Cunningham; Tommy Bowe, Seamus Mallon, Paul Steinmetz, Tyrone Howe; Adam Larkin, Kieran Campbell; Ronan McCormack, Paul Shields, Rod Moore; Gary Longwell, Matt McCullough; Andy Ward, Neil Best, Roger Wilson.
Replacements: Nigel Brady, Bryan Young, Tim Barker, Campbell Feather, Neil Doak, Scott Young, Shane Stewart.
Referee - Andy Ireland (SRU).
Other fixtures this weekend.
Neath-Swansea Ospreys v Newport Gwent Dragons, St Helen s, 7.05pm live on BBC Wales. Referee: Olan Trevor (IRFU).
Sunday. Connacht v Leinster, The Sportsground, 2.30pm. Referee: Nigel Williams (WRU).
Llanelli Scarlets v Cardiff Blues, Stradey Park, 3.30pm live on S4C. Referee: George Clancy (IRFU).
Edinburgh Rugby v The Borders, Murrayfield, 7pm. Referee: Neil Ballard (WRU).