England lock Mouritz Botha is leaving Saracens to join the Durban-based Sharks in South Africa.
Saracens have "reluctantly" agreed to release Botha, 32, who will formally sign for his new club on 1 January.
"Mouritz has been a massive part of our squad and our culture and we are very sorry to see him leave," said director of rugby Mark McCall.
"However, this is a great opportunity to play for one of the top teams in the Super 15."
South Africa-born Botha, who won 10 England caps between 2011 and 2012, has been with Sarries for five-and-a-half years, making 142 appearances since arriving from Bedford Blues in 2009.
He said: "Saracens will always be important to me and it's difficult to leave so many friends in what remains a unique sporting environment.
"But the Sharks are trying to build something special in Durban. This will be a great rugby challenge for me and a great adventure for my young family."