This is much easier than it looks.
Before you start the round, go to Road to the Masters - My Career - Options - Game Options and turn the difficulty to tournament. Then go to Road to the Masters, then Next Event and play the first hole of the event and once it loads up with the second hole, save and exit the game. From there, go to Options - Settings and turn the difficulty to amateur, then go back to the Road to the Masters and hit load last hole. Complete the game on this setting until you are on the 18th tee, save and exit again, and turn the difficulty back up to tournament. Complete the 18th hole on this setting. This achievement will unlock along with no focus, even if you used focus during the 16 holes completed on amateur.
This is also a great way of levelling up if you don't mind playing with the options a lot.