The two matches in each Pool will have simultaneous kick-offs and with priceless home advantage up for grabs there is everything to play for on the final weekend of Pool action of the 16th tournament.
And Dai Young, the Cardiff Blues Director of Rugby, believes Northampton Saints, the 2000 champions, can win their Pool 1 contest at Castres Olympique in Round 6 and become the first English club since Bath in 2001 / 2002 to make it six out of six.
"I fancy Northampton," said Young, who guided the Blues to the Amlin Challenge Cup crown last season. "It's never going to be easy out there but if you look at how Castres beat us in France it was through a lot of pressure early in the match, through field position and then a big scrum and a driving line-out.
"But I think Northampton can match them in those areas. If you look at how Northampton won the game at home once again there were scrum penalties. I think it will be a territory-based game and the two No 10s will play a big factor. They'll both be looking for field position.
"I fancy Northampton to just do enough to win that game and get a home quarter-final."
Defending champions Toulouse are also five from five so far and travel to Adams Park on Sunday looking to make it a club record 12 successive tournament wins but wary of a London Wasps side stung by a Round 5 defeat at Glasgow Warriors that ended their hopes of topping Pool 6.
However, no team has ever gone on to win the trophy - or even qualify for the final - after making it a clean sweep in the Pool stages.