So, did you see the Olympic Gold medal match? Did you see all of the "guessing"?
Murray hardly (if ever) guesses, since he has the best return in Pro tennis. Fed was doing it more than his average, since he was desperate to break.
I am sure you can find the videos on the net somewhere.
Here is a brief and incomplete list:
1st set, 5th game, 4th point, 2nd serve.
2nd set, 3rd game, 5th deuce, 2nd serve.
2nd set, 5th game, 1st and 4th points.
2nd set, 7th game, 6th point, second serve.