Bath back-row Zach Mercer is to leave the club at the end of the season and join French side Montpellier, with South African number eight Jaco Coetzee coming in to replace him.
Mercer, 23, came up through Bath's academy ranks and played for England against the Barbarians in 2018.
The ex-England youth player has scored one try in six appearances this season.
Coetzee, 24, will join from Super Rugby's Stormers and helped Western Province win the 2017 Currie Cup.
"It has been a long-standing dream of mine to play in France - the game is physical and will suit my playing style," Mercer told the Bath website.
"I've spent a huge part of my career with the Blue, Black and Whites and I will be forever grateful for the opportunities this has brought me.
Director of rugby Stuart Hooper added: "With Jaco's arrival, we feel we have an unbelievably exciting addition to the squad who will be available to play for the club for the full season.
"He's an intimidating ball carrier and will cause huge problems for our opposition no matter where he is on the field. I'm looking forward to seeing him compete with our current group of strong back rowers to get on the field for us."