That meant the Blues were able to overtake the Ospreys, the reigning Magners League champions, and take over the top spot among the four Welsh teams. If they win their remaining two matches, both Welsh derbies, they will be guaranteed a semi-final slot.
However, the Ospreys can still make the Play-Offs if the Dragons and Scarlets beat the Blues and the champions win their final game in Italy against Aironi.
A Scarlets win over the Blues on the final Friday could also see them creep into the Play-Off reckoning if the Blues and Ospreys fail to pick up any more wins or, in the case of the Blues, points.
The Scarlets picked up a bonus point in their 37-29 win over Glasgow at Firhill. There were two tries for Wales wing Morgan Stoddart in that victory, while the Dragons fell 27-15 at Edinburgh.
That defeat, which featured an 11th try of the season for Aled Brew, meant the Dragons will play in the Amlin Challenge Cup next season as they cannot now pass the Scarlets to get among the top three Welsh regions in the final Magners League table.
But the Rodney Parade outfit can still have a huge bearing on what happens at the top with two home games to come. They meet the Blues this week and then host third placed Ulster in Round 22.
If they can stop Ulster from gaining a point in that game they could help two Welsh teams to qualify for the Play-Offs. With 10 points still to play for the Blues have the ability to finish in second place if Leinster fail to beat Glasgow at home in their final outing.
The top two teams - Munster are already guaranteed top ranking - will have home advantage in the semi-finals - 1 v 4 and 2 v 3.
MAGNERS LEAGUES STANDINGS
P W D L PF PA Diff TF Pts
1 Munster 21 18 0 3 474 321 153 41 79
2 Leinster 21 14 1 6 457 333 124 46 65
3 Ulster 21 14 1 6 460 405 55 41 63
4 Blues 20 13 1 6 441 326 115 33 60
5 Ospreys 21 11 1 9 541 408 133 56 59
6 Scarlets 21 11 1 9 465 430 35 45 57