HERE ARE THE WINNERS OF OUR CHRISTMAS COMPETITION!
PRIMARY: ANA JUARRANZ SEGOVIA

 
SECONDARY: VÍCTOR EXPÓSITO

 
BACHILLERATO: PABLO MARTÍN BAHÓN

'A whole new ball game' is a situation which is different from anything that has happened before.
Examples:
I thought I was good at speaking English in terms of day-to-day conversation. But working as a professional translator is a whole new ball game; I have to be much more accurate.

Tom says working as a manager for the first time is a whole new ball game.

I used to go jogging every weekend, but running marathons is a whole new ball game.