Scotland assistant coach Matt Taylor is quitting to join the Australia national team with immediate effect.
It means Gregor Townsend is looking for a new No.2 ahead of the 2020 Six Nations.
Scotland kick off the Championship against Ireland in Dublin on 1 February.
Taylor, 47, will work with Dave Rennie as defence coach in the Australia set-up. Rennie, the Glasgow Warriors head coach, is leaving Scotstoun to take charge of the Wallabies at the end of the season.
Taylor is moving immediately which will allow Scotland to freshen up their coaching set-up after a disappointing Rugby World Cup where they failed to qualify from the group stage.
He has been recruited by Scott Johnson, Rugby Australia's director of rugby, who used to hold the same position with the SRU.
Johnson told the Rugby Australia website: “Matt is someone who I have had a lot do with, and someone I regard very highly as a coach.
“He’s a quality coach who has the experience, skillset, and personality that we believe will fit really well in the coaching team we have assembled.
“It is great for Australian Rugby to be able to bring back someone of Matt’s calibre. As I said at the start of this process, we wanted a strong Australian flavour and we’d do everything in our power to make sure we get what we think is a quality coaching group for the Wallabies.”
Brisbane-born Taylor joined the Scottish coaching system in 2012 from Queensland Reds with whom he won the Super Rugby title.
He was initially given a dual role covering Glasgow Warriors and Scotland’s defence, and alongside Townsend helped the Warriors win the Pro12 grand final in 2015.
Townsend paid tribute to his departing assistant, saying: “It’s been a real pleasure working with Matt both at Glasgow and Scotland.
“Matt is passionate about coaching - helping players and the team improve, and also continually striving to be a better coach. He can be really proud of a number of achievements he helped create over an eight-year period in Scottish rugby.
"We wish him all the best in his new challenge, working with the country he grew up in. I’m sure he’ll do a great job.”
Taylor, whose parent are from Fife and who played for Aberdeen Grammar, Edinburgh and the Border Reivers, said in a statement: “I would like to thank the players and the staff of both Scotland and Glasgow Warriors for the friendship they have shown to me and my family over the past eight years.
“The moments we’ve shared through this period will stay with us for many more to come. The Calcutta Cup win in 2018 with Scotland and winning the Pro12 title in 2015 with Glasgow are ones which will always remain vivid.
“I’d like to take the opportunity to thank my family – Kirsten, Brianna and Cruz – who came to Scotland to start a new life and support me. They have done so in spades.
“We made Scotland our home and have made so many close and lifelong friends. Although the move back to Australia opens a new chapter in our lives, it's not a case of closing the book here. We will always stay connected to our friends and family and particularly the Scotland national team.
“I’m going to miss Flower of Scotland, the roar of BT Murrayfield, the passion of Scotstoun and – most of all – the celebrations in the changing room after a game with players and staff alike, but the time is right to take on a new challenge.”