The provinces claimed 19 out of a possible 20 points over the weekend, as Munster and Leinster kept up the Irish 1-2 at the top of the GUINNESS PRO12, Ulster moved up to fifth place and Connacht's second successive home win also saw them gain ground.
Connacht Rugby have confirmed that Pat Lam has announced he will be leaving the province at the end of the 2016/17 season. The former Samoa captain, currently in his fourth season with Connacht, will finish up next summer to take up a new coaching role.
Man-of-the-match Ruan Pienaar inspired Ulster to a 35-22 bonus point victory over Cardiff Blues at BT Sport Cardiff Arms Park, with Stuart McCloskey, Chris Henry and Louis Ludik all making try-scoring returns in the white jersey.
After last week's home tie with Zebre was postponed, Ulster will be straining at the leash for this evening's GUINNESS PRO12 clash with Cardiff Blues as they chase their first away win since the end of September.
Overcoming a second half onslaught from Glasgow Warriors at Scotstoun Stadium, Munster recorded another impressive away win, doing so in dramatic fashion with a 76th minute drop goal from out-half Ian Keatley.
Munster's first test as new GUINNESS PRO12 leaders is a tough one, renewing rivalries with an international-laden Glasgow side who will want to gain some revenge for October's heavy Champions Cup defeat in Limerick.
Munster director of rugby Rassie Erasmus has made six changes for Friday's GUINNESS PRO12 encounter with Glasgow Warriors at Scotstoun Stadium (kick-off 7.35pm). Peter O'Mahony returns to captain the province with his back row colleague Tommy O'Donnell set for his 100th PRO12 appearance.
Having featured in every game of the campaign to date, Munster winger Darren Sweetnam and hooker Niall Scannell are this week preparing for what is consistently a formidable challenge in any GUINNESS PRO12 season - a trip to Scotstoun.
Ahead of Leinster's meeting with the Newport Gwent Dragons next Saturday, scrum half Luke McGrath reflected on a disappointing result against the Scarlets and spoke about bouncing back against a tricky Dragons side.
The battle to reach the GUINNESS PRO12 final is closing in on the halfway point and already it is impossible to project just who will reach the semi-finals come May. Munster go into round 10 as table toppers - the fourth team to do so this season - but fellow former champions Leinster and the Ospreys are in hot pursuit.