Leinster have past history with all three of their Pool 2 opponents in the European Rugby Champions Cup. Indeed, they lined out against two of them - London Wasps and Castres Olympique - in the last 13 months.
EUROPEAN RUGBY CHAMPIONS CUP - POOL 2:
Today's draw in Neuchatel, Switzerland saw top seeds Leinster placed in Pool 2 where they will battle it out with Castres and English sides Harlequins and Wasps.
The province beat Castres home and away in the 2013/14 Heineken Cup, their away win breaking the French club's year-long unbeaten home record.
Leinster last faced Harlequins in European competition on the way to winning the Heineken Cup in 2009. Back then they won a tight game at the Stoop by a single point to set up a Croke Park semi-final showdown with Munster.
Meanwhile, in April of last year, the Blues got the better of Wasps in a free-scoring Amlin Challenge Cup quarter-final. Five tries from Ian Madigan, Mike Ross, Isa Nacewa, Rob Kearney and Gordon D'Arcy all contributed to a 48-28 victory.
Giving his reaction to the Champions Cup draw, hooker Sean Cronin said: "Usually there's only one group of death, but they all look tough pools. We've got two trips to London which all the boys will be looking forward to.
"Hopefully there are a few Irish living in London who fancy coming along and giving us their support, as they did at Northampton last season.
"We had Castres in that pool as well. We played poorly at home and just squeezed out the win but did well out there when we knew it was do-or-die for qualifying.
"But they have since reached a second Top14 final in a row so that says everything about their strength. They may not be the first French team people talk about, but you don't reach two finals in a row and win the title without being a top-quality team."
Reflecting on Leinster's exit from the Heineken Cup at the quarter-final stage, he added: "We were disappointed with ourselves this season. We work so hard to progress from a pool that including Northampton, Castres and Ospreys and then felt we let ourselves down in the quarter-final at Toulon.
"Leinster have a proud tradition in Europe and it will be a huge focus for us next season. We are judged on winning trophies and it was great to lift the PRO12 title and send everyone off for the summer break with a huge boost but we want to prove ourselves again in Europe next season, even though it will be strange not to have Leo (Cullen) and Brian (O'Driscoll) on the pitch."
Beaten semi-finalists this past season, Leinster have been handed the stiffest of draws in the 2015/16 European Champions Cup - they have reigning European champions Toulon, Aviva Premiership runners-up Bath and resurgent Wasps for company in Pool 5.
Looking forward to the new GUINNESS PRO12 season, Connacht captain John Muldoon said: "We've a lot of younger guys who have big years ahead of them and a few big name signings who will hopefully be able to fit into the system and work hard among the ethos of Connacht Rugby."
Irish Rugby TV was at the launch of the GUINNESS PRO12 and we caught up with Jamie Heaslip, Pat Lam, John Muldoon, Matt O'Connor and Rory Sheridan of Diageo as the new sponsor gets ready to kick off an exciting season.
Out-half Dan Parks had a vital role in Connacht's historic Heineken Cup triumph in Toulouse, kicking two penalties, a drop goal and the touchline conversion of Kieran Marmion's try. He spoke to Rob Murphy after the game.
Rob Murphy caught up with Gavin Duffy after Connacht's inspirational defeat of Toulouse in the Heineken Cup, with the Mayo man giving an insight into how they produced such a high quality performance against the French giants.
Young scrum half Kieran Marmion was one of Connacht's star performers in their famous 16-14 Heineken Cup victory away to Toulouse, scoring a crucial second half try and picking up the man-of-the-match award.
Giving his reaction after Connacht's historic 16-14 win away to Toulouse, head coach Pat Lam said: "The belief's been there, we knew that this performance was not far away. To come here in a massive game with the side they put out is an unbelievable effort (from us) and I'm so proud of the guys."
Fergus McFadden, who helped to launch the Ulster Bank League awards in Dublin, spoke afterwards about his recovery from a fractured hand, previewed Leinster's back-to-back games against Northampton Saints and reflected on his involvement in the GUINNESS Series with Ireland.
Out-half Craig Ronaldson, who has made a successful transition from Ulster Bank League rugby with Lansdowne to a professional contract with Connacht, talks about the step up to this level of rugby, the importance of the league in providing game-time and a shop window for players and he also previews the province's back-to-back clashes with Toulouse.
Connacht head coach Pat Lam was proud of the performance his players produced in their 23-17 Heineken Cup defeat to Saracens, but he was left frustrated by some of referee Pascal Gauzere's decisions in a tight second half.
The Irish launch of the 2013/14 Heineken Cup took place in Dublin last week and Irish Rugby TV caught up with Sky Sports commentator Stuart Barnes to chat about his favourite Heineken Cup memories and get his thoughts on this season's tournament.