Wales defence coach Byron Hayward has left his role with immediate effect just five days before Wayne Pivac's side start their Autumn Nations Cup campaign against Ireland.
The former Wales under-20 coach, who has left by mutual agreement, previously worked with Pivac for the Scarlets region and was appointed to his senior national team role alongside him in 2019.
Wales head into the new tournament, starting on Friday, after their worst Six Nations campaign since 2007.
Pivac's side won only once in the interrupted championship, which has just finished, and have lost five matches in a row since a February victory over Italy.
"I would like to thank Byron for all his hard work with Wales and thank him for his honesty in recent meetings," Pivac said in a Welsh Rugby Union statement.
"I have worked alongside Byron for six-and-a-half years. He is a dedicated coach that has had great success in his career.
"On reflection of the last campaign it was mutually decided that the best way forward for Wales and for Byron is for him to step down from his role."
Pivac said the existing coaching team would manage the defence for the four matches in the Autumn Nations before a full-time replacement was appointed
Hayward said: "I have thoroughly enjoyed my time with Wales and it was an honour to coach my country.
"As I have always said from day one, the team comes first and upon reflection of the last campaign with Wayne we felt it was best for me to step aside."