The race for quarter-final qualification is entering the home straight with the majority of the coveted eight places set to go all the way to the completion of Round 6 matches.
However, Harlequins hold a commanding six points lead at the top of Pool 4 and a Round 5 win over Ulster Rugby at Ravenhill would guarantee Quins quarter-final qualification - but not all important ranking with home advantage going to the best four Pool winners.
And Cardiff Blues are in the Pool 6 driving seat, four points clear of Gloucester Rugby with their Kingsholm Sunday showdown potentially the clash of Round 5.
Since the format of the two best runners-up qualifying for the quarter-finals as the No 7 and No 8 ranked teams has been in operation since the 1999 / 2000 season and bonus points coming into the equation in season 2003 / 2004, here are some quarter-final qualification pointers:
• No team has qualified as Pool winners on less than four wins.
• No team has qualified as one of the best runners-up on less than four wins.
• Since bonus points were introduced no team has qualified as a Pool winner on less than 18 points (Stade Français Paris in 2003 / 2004).
• Since bonus points were introduced no team has qualified as one of the best runners-up on less than 19 points (Leicester Tigers in 2004 / 2005)
The maximum points and wins attainable by each team on current standings are: