WATCH: Federer wishes Boks well ahead of Japan encounter

File: Coach Rassie Erasmus named an identical matchday 23 to their 49-3 victory over Italy earlier in the tournament, with a six-two forwards-backs split on the bench -- indicating they will hit Japan with some heavy artillery upfront.

FILE: Springboks and England's top players fuel the line up for the Rugby World Cup. 

Getty Images / Anthony Au-Yeung

JOHANNESBURG - A pleasant surprise for the Springboks ahead of their crucial quarter-final clash against Japan on Sunday.

Messages of support have been coming in, and the latest is from none other than the tennis great, Roger Federer.

READ: Japan hopes for a second upset in Springboks clash

The 20-time grand slam tennis champion's mother is South African and he reportedly practiced scrums with his dad when was younger. 

“Let’s go Springboks! I know you guys can do it and I’m supporting you guys. I’m not your number one fan because I don’t know all the rules, but I will be supporting you,” Federer told CNN.