And it will be a special landmark weekend for former Heineken Cup champions Leicester Tigers and Leinster as they both play their 100th tournament match to join Toulouse and Munster as centurions.
Leicester Tigers hit three figures first, at Perpignan on Saturday, with Leinster joining them the following day at ASM Clermont Auvergne.
Meanwhile, four times champions Toulouse get the Round 3 ball rolling with their clash against Glasgow Warriors in the only Friday night contest while fellow Scottish team Edinburgh are still searching for their first win of the campaign.
However, Edinburgh travel to France to face Castres Olympique in the knowledge they have won on French soil once before - 13-6 against the same opponents at Stade Pierre Antoine in the 2008 / 2009 tournament.
"We should be okay away from home because we approach games very similarly to how we do at home, we do not change dramatically how we play," said Edinburgh head coach Rob Moffat.
"I think a lot of teams struggle in away games because the mindset is conservative compared to that at home. Ours is not so we approach away games very similarly to home games. We will certainly not go out to try and restrict the opposition or calm things down in the first 20 minutes, we will play.
"We know Castres as we played them a few years ago and beat them - they are the only French team we've beaten away from home so we're pretty familiar with them.
"And I really like the back-to-back element, it is something else about the Heineken Cup which is a bit different and a bit special.
"You play a team one week and then the next so it's not a case of waiting three or four months and that means you have got to be smart. It brings different challenges and that is fantastic."