Ospreys have recruited defence coach Brad Davis from Wasps.
The Australian joined Wasps in 2013 having previously coached at Castleford Tigers rugby league club and Bath in the Aviva Premiership.
"We are under resourced in comparison to our competitors, and the board have agreed increased investment into the support team," said managing director Andrew Millward.
"This is the first of a number of planned changes."
Davis, a former rugby league player, had the option of remaining as one of ex-Wales prop Dai Young's assistants at Wasps.
"It is the nature of professional sport that players and coaches move on," said Young.
"Brad has done a great job for Wasps over the past three seasons and I would like to thank him for his hard work and efforts during that period."