Both home semi-finals and top spot at the end of the regular league season remain up for grabs after Leinster were beaten by Connacht on Wednesday night.
Having already qualified for the knockout stages with three games to spare, the league leaders arrived in Galway knowing victory would secure a first-place finish and guarantee a home semi-final in the inaugural Magners League Play-Offs.
But the 2008 champions fell to a 27-13 defeat at The Sportsground which means they still require three more match points from their two remaining games to finish top of the pile.
Leinster can still be caught by Glasgow Warriors and either the Ospreys or Munster who face each other at Thomond Park this Saturday.
Despite last night’s slip up, Leinster remain heavy favourites to reach the final four as top seeds.
Michael Cheika’s men still have a seven-point lead over Munster and the Ospreys and an eight-point cushion between themselves and Glasgow with just two games remaining.
The team that finishes top of the regular league will go into the semi-finals with the added incentive of knowing that victory at that stage would earn them home advantage in the Magners League Grand Final on Saturday, May 29.
Leinster may have already secured a semi-final spot but the race for the other three Play-Off places is still wide open with the Ospreys (43 points), Munster (43), Glasgow Warriors (42), Edinburgh (40), Newport Gwent Dragons (38) and Cardiff Blues (36) all in with a mathematical chance of a top-four finish.
Leinster are back in action on Friday night at Glasgow, with the Blues and Dragons going head-to-head in Newport on the same night.
Munster host the Ospreys on Saturday, while fifth-placed Edinburgh welcome struggling Ulster to Murrayfield on Sunday.
And while things are really hotting up at the top of the table, a similar story is developing at the other end of the scale.
Connacht’s fine victory over Leinster has seen them climb above the Scarlets and off the bottom of the table. Those two sides face each other in Llanelli on Sunday, with Connacht knowing a win would ensure they avoid finishing in last place.
Michael Bradley’s squad also know that victory could see them overtake Ulster in the race for the third and final Irish place in next year’s Heineken Cup.
Intriguingly, Connacht travel to Belfast on the last day of the regular season for what could be a mouth-watering winner-takes-all encounter at Ravenhill.
Magners League REMAINING FIXTURES
Friday, April 23
Newport Gwent Dragons v Cardiff Blues – Rodney Parade 19:05
Glasgow Warriors v Leinster – Firhill Stadium 20:00
Saturday, April 24
Munster v Ospreys – Thomond Park 18:30
Sunday, April 25
Scarlets v Connacht – Parc y Scarlets 14:05
Edinburgh v Ulster – Murrayfield 16:05
Cardiff Blues v Munster – Cardiff City Stadium
Leinster v Edinburgh – RDS
Ospreys v Dragons – Liberty Stadium
Scarlets v Warriors – Parc y Scarlets
Ulster v Connacht – Ravenhill
Magners League Play-Off Semi-Finals
ML1 v ML 4
ML2 v ML 3
Saturday, May 29
Magners League Grand Final – 18:30