The Scarlets will take on Toulon, London Irish and Bayonne in the 2019-20 European Challenge Cup following the draw in Lausanne.
The French giants will be no strangers to Llanelli, having been beaten on their last two visits to Parc y Scarlets in the Champions Cup.
Two years ago, the former kings of Europe were edged out 30-27 in a thrilling pool clash which saw the Scarlets secure their place in the knockout stages.
The sides have met seven times in European competition in all, including a quarter-final in the second tier competition in 2010 when the likes of Jonny Wilkinson and Sonny Bill Williams featured for the French side.
Toulon also have Wales international scrum-half Rhys Webb in their ranks.
London Irish and the Scarlets have clashed on four previous occasions in European competition, with the Scarlets coming out on top each time.
The Madejski Stadium will hold mixed memories for Scarlets fans, though, having been the venue for their heartbreaking semi-final loss to Northampton Saints in 2000.
The draw also sees new Scarlets coaches Glenn Delaney and Richard Whiffin return to their old club.
As for Bayonne, promoted from French Pro2 last season, this will be the first time the sides have met in European competition.
Scarlets general manager of rugby Jon Daniels said: “It is an exciting draw for us. It seems we can’t get away from Toulon in European rugby, they are three-times winners of the Champions Cup and a side stacked with international quality.
“We have enjoyed some memorable matches against them in recent years and look forward to welcoming them to Parc y Scarlets again.
“London Irish have made some big signings over the summer and there is an added dynamic to the games in that two new members of our coaching team, Glenn Delaney and Richard Whiffin, used to coach there.
“Bayonne are a side we don’t know a huge amount of, but they recently won promotion from the French second division, have a passionate following and we are well aware how tough travelling to play in France will be.
“There are four former champions of Europe in this year’s Challenge Cup and we are excited by the challenge in store.”
European Challenge Cup draw 2019-20
Pool 1: Castres Olympique, Worcester Warriors, Dragons, Enisei-STM
Pool 2: Scarlets, RC Toulon, London Irish, Bayonne
Pool 3: Wasps, Edinburgh Rugby, Bordeaux-Begles, Agen
Pool 4: Stade Francais Paris, Bristol Bears, Zebre Rugby Club, Brive
Pool 5: Cardiff Blues, Leicester Tigers, Pau, Rugby Calvisano
EPCR weekends – 2019/20 season
Round 1: 15/16/17 November 2019
Round 2: 22/23/24 November 2019
Round 3: 6/7/8 December 2019
Round 4: 13/14/15 December 2019
Round 5: 10/11/12 January 2020
Round 6: 17/18/19 January 2020
Quarter-finals: 3/4/5 April 2020
Semi-finals: 1/2/3 May 2020
Admission to all three home games will be part of the Scarlets season ticket.
For information on buying a season ticket for 2019-20 go to firstname.lastname@example.org