Two former Heineken Cup winners - Northampton Saints and Brive - and two of last season's Heineken Cup semi-finalists, London Irish and Saracens, all top their European Challenge Cup Pools with two rounds of matches to go.
They are joined by last season's tournament finalists Worcester Warriors in the race for quarter-final qualification with the five Pool winners and three best runners-up going through to the knock-out stages.
Northampton Saints, who have taken a maximum five points from all four of their matches, have an unassailable 12-points lead in Pool 2 and are through to the last eight with two matches to spare and resume Euro action on the back of a morale boosting 17-13 win over fierce Midlands neighbours Leicester Tigers.
But Bruce Reihana's team still have the carrot of home advantage in the quarter-finals, and possibly in the semi-finals, to shoot for when they face French sides Montpellier away and finally Toulon at Franklin's Gardens.
"We are delighted to have qualified for the knock-out stages but we certainly do not regard the job as done and dusted," said Jim Mallinder, the Saints Director of Rugby.
"Everyone appreciates how important it is to earn home advantage in the quarter-finals so we will be pushing on against both Montpellier on Thursday night and then Toulon in Round 6 nine days later.
"French clubs are always capable of rising to the challenge on their home turf and, although we beat Montpellier with a try bonus point at Franklin's Gardens, we will be taking nothing for granted over at Stade Yves du Manoir.
"It is great being back in Europe after a season away and we have enjoyed our tournament matches so far but we are determined to give ourselves the best possible chance in the quarter-finals and that means there will be no complacency from the Saints over the next two weekends."
But elsewhere knock-out places are still up for grabs with Brive just two points ahead of Newcastle Falcons, the match between the clubs at Kingston Park in Round 5 a potential group decider.
And they certainly already know almost all there is to know about each other.
It will be the eighth European Challenge Cup meeting between the clubs in just four successive seasons with the score standing at 5-2 to the Falcons after Brive won their home match 36-22 in Round 2 back in October.