The Scottish and Welsh rugby authorities are to switch their criteria for European qualification to the new-look Celtic League from next season.
Both countries have agreed to award Heineken Cup places to the top two Scottish and top four Welsh sides in the competition.
The Irish Rugby Football Union have also confirmed they will use performances in the Celtic League as one of the key indicators of their European ratings.
Ireland have held the Celtic League trophy for the past two years following the successes of Leinster and Munster in the finals of 2002 and 2003 and have two guaranteed Heineken Cup places.
The performances of provincial sides Ulster, Munster, Leinster and Connacht will be graded over the season with the highest ranked going forward to the elite European competition.
Celtic League organisers believe the decision will significantly increase the status of the competition.
"This is just the kind of boost to the tournament's stature, standing and credibility that we have been looking for," said Keith Grainger, the competition's newly appointed tournament director.
"It means there is even more than champion or cup-winner titles at stake for all the teams.
"Now that the three Unions and their clubs have agreed to a home and away formula for the Celtic League competition, it will provide more regular and even higher quality rugby than in its first two seasons," he said.
"As far as the Scots are concerned, it will be a straight shoot-out between their three teams for the guaranteed two places in the Heineken Cup.
"It will be the same for Wales, with their top-four finishers claiming their European slots in the 2004/2005 season".