And then there were three.
With three rounds left, only three teams are left in the running for the third Celtic League crown ... and this weekend is crucial as things get tight at the top and nervous at the bottom.
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At Netherdale, it's the leaders against the cellar-dwellers as Ulster travel to The Borders, who are desperate to avoid finishing behind Scottish rivals Glasgow and therefore lose their berth in the Heineken Cup next season.
Glasgow also have a tough assignment, travelling to Wrexham's Racecourse Ground to take on the Llanelli Scarlets, who know a bonus-point victory is essential as they keep a close eye on Ulster.
The Dragons are poised behind the top two and they know any slip-up will wreck their title hopes. In fact, unless the Rodney Parade side get 14 or 15 out of the possible 15 points in the next three games, they will have little chance of League glory.
They travel to Connacht, who will be smarting after Sunday's heart-breaking match against NEC Harlequins. The little Irish province won the match 23-18 but lost the series by four points to miss out on a berth in the Parker Pen Challenge Cup final and a chance of moving up to the Heineken Cup next season.
In other matches, the Cardiff Blues have to beat Munster at the Arms Park to have any chance of Heineken Cup rugby next season, while Edinburgh host the Celtic Warriors at Meadowbank.
The Neath-Swansea Ospreys are the in-form team of the past couple of months, securing 23 from a possible 30 points, but they have to travel to Leinster's Donnybrook fortress on Friday night. A loss there will give the Blues hopes of passing their Welsh rivals in the last two games of the season.Note: In the event of teams finishing level on match points at the end of the season, the winner will be decided by points difference. As we enter round 20, Ulster have a +235 difference, the Scarlets +192 and The Dragons +96. Ironically, The Dragons have won more games (14) than their rivals, but bonus points give Ulster and the Scarlets a two-point lead at the top.