Boris Becker is best known for winning three Wimbledon titles and six grand slam tennis tournaments.
But the German is also a huge football fan. Indeed Becker -- who turned 50 last week -- once served on the board of Bayern Munich and is also a supporter of Chelsea.
He has analyzed football matches on television and was even a pitch-side reporter in the 2006 World Cup final between Italy and France.
So he was game to take CNN's World Cup quiz.
There were seven questions -- some were very tough ...