Former South Africa captain John Smit says Saracens and England hooker Jamie George is "the real deal".
Smit signed for Saracens in 2011 and ended his playing career at the club, leaving for a role as the chief executive of South African side Sharks in 2013.
The former hooker said: "The beautiful thing about Jamie is that he doesn't look the part but I could never keep up with him at fitness, I could never run with him.
"He's got an engine that just has no boundaries."
Smit led the Springboks to World Cup glory in 2007 and retired from international rugby in 2011 with 111 caps.