Harlequins have agreed a deal to sign Montpellier fly-half Demetri Catrakilis ahead of the 2017-18 season.
The 27-year-old joined the French Top 14 club in 2015 and was a member of the side which beat Quins in the European Challenge Cup final in May.
South Africa-born Catrakilis has previously played for Super Rugby franchises Southern Kings and Stormers in his homeland.
He also won the Currie Cup twice with Western Province.
"The fly-half position is hugely influential in the game and Demetri has all the physical and mental attributes required to dominate at the highest level," Harlequins director of rugby John Kingston said.
"Our ability to secure this signing already is a reflection of our commitment to focus hugely on Harlequins' recruitment needs for the future."
Quins have not disclosed the length of Catrakilis' contract at The Stoop.