Former Wales scrum-half Dwayne Peel will return to Scarlets as head coach after being released from a contract with Cardiff Blues.
The appointment of Peel, 39, will see current head coach Glenn Delaney take up the position of director of rugby.
Peel was originally set to come back to Wales from Ulster on a three-year deal as senior assistant coach at Cardiff.
Cardiff Blues have appointed Worcester Warriors backs coach Matt Sherratt as assistant coach in Peel's place.
Sherratt was previously backs and attack coach at Cardiff Blues, who announced earlier this month that Dai Young had signed a long-term contract as director of rugby.
"The Scarlets has always meant a massive amount to me and my family and I'm thrilled to be returning to my home club as head coach," said Peel.
"I have been part of some incredible occasions with the Scarlets and I know everyone involved with the club has ambitions to be challenging regularly for silverware and competing with the top sides in Europe.
"As a player, I have experienced first hand the passion of the Scarlets fans, there is a special bond between the supporters and the club and I'm looking forward to seeing everyone back at Parc y Scarlets next season."
Peel's playing career started in Llanelli with the Scarlets and he also played for Sale and Bristol, while at international level he helped Wales win two Grand Slams and started three Tests for the British and Irish Lions in 2005.
The scrum-half spent eight years as a player in Llanelli, before a year coaching with Bristol and eventually joining Ulster in 2017.
"It is fantastic news for Scarlets fans that a legend of the club like Dwayne is coming home," said Scarlets executive chairman Simon Muderack.
"His outstanding playing career speaks for itself, but he has also become a widely-respected coach during spells with Bristol and more recently Ulster.
"Dwayne understands what the Scarlets is all about, he knows the 'Scarlets Way' and he is hugely excited about coming back to West Wales to take up this role in the coaching team."
Blues turn to Sherratt
With Peel's move to Scarlets now confirmed, Cardiff Blues have recruited former coach Sherratt.
Sherratt worked for Cardiff Blues as backs and attack coach between 2016 and 2017 before joining Ospreys and then moving on to Worcester in 2020.
The Cardiff hierarchy has changed since Peel's appointment, with Young handed the director of rugby role after the departure of previous head coach John Mulvihill.
Cardiff were reluctant to let Peel go but feel Sherratt is an ideal alternative attack coach to work with Young.
Sherratt said: "I thoroughly enjoyed my time at Cardiff previously and look back on it as some of my most successful and fondest times in the sport.
"There is an enormous amount of talent in the squad, with plenty of room for further improvement, and I know the majority of players and staff very well.
"I feel like I am returning a better coach, with the benefit of the further experiences gained at the Ospreys and Worcester.
"I have enormous respect for Dai, and we have always got on well, so I am looking forward to working with him as we enter a new, exciting era."