London - Hashim Amla is to replace Graeme Smith at Surrey after the former Proteas captain was ruled out for the rest of the English season with a fractured right knee.
Smith is now set to return to South Africa, with Gary Wilson taking over the captaincy of south London-based Surrey.
Opening batsman Smith has been beset by injuries since he signed a three-year deal with Surrey in 2012.
Last year his first season at The Oval was cut short when he needed ankle surgery.
Alec Stewart, Surrey's director of cricket, insisted Smith had done all he possibly could to play through the pain barrier but that surgery was now the only option for the 33-year-old left-hander.
"He's done his very best to play through a lot of pain," Stewart told BBC London.
"He's taken a lot of pain killers to get through the last 10 days or so," the former England captain added.
"But the scans showed the fracture and it was non-negotiable, he had to go for this operation.
"You have to accept it, and the good thing is we've been able to get Hashim Amla over at short notice.
"Cricket South Africa have been excellent with their dealings and we'll have him for the majority of June and then we'll see where we are after that."
Smith retired from international cricket after the final Test against Australia, in Cape Town in March, having scored over 9 000 runs in 117 Tests at an average of nearly 49 with 27 hundreds.
However, he stressed his exit from South Africa duty in no way affected his commitment to Surrey.
It was at The Oval where Amla became the first South Africa batsman to score a Test triple hundred when he made 311 not out against England in 2012.