After the surprises thrown up by Glasgow Warriors and Border Reivers in week three of the Celtic League, round four promises to be just as exciting with league leaders Ulster travelling to the Dragons on Saturday, looking for a third straight win of the season. However, the Ulstermen have never won at Rodney Parade and with the Dragons looking to bounce back from consecutive defeats, their first home game of the season promises to be a great contest.
Should Ulster slip up Edinburgh Gunners, who lost to the leaders last Friday, could go top if they can overcome the Ospreys at Murrayfield on Sunday. For their part the Ospreys will be looking for a happier trip north than last weekend when they lost to the Reivers; they have never lost to the Gunners in the Celtic League.
The round kicks off, however, with last weekend's shock losers, Munster, at home to the Scarlets. That game has been switched to Cork after vandalism left Munster's Thomond Park ground in Limerick unplayable.
Despite their win over the Ospreys the Reivers are still only a point away from bottom side Connacht, and will hope that a first ever away win in the Celtic League will put some space between themselves and bottom place.
Saturday also sees Blues travel to Glasgow Warriors who will be buoyed by their win over Munster. The form book suggests a Warriors win with the Blues having only taken the points once in their last seven visits to Scotland.
A special video package as Pontypridd claimed the double for the first time in their history by winning the Principality Premiership final, including match build-up, highlights, post match reaction and dressing room celebrations.