"Former team-mate" only to indicate that the encroaching player might have a better idea than most which way the ball was going and thus which way the GK should dive, especially after seeing the kicker's run up. Defender encroaches and is gesticualting to the GK who goes the right way and saves. If the defender shouted "go right" and the GK dived that way and saved it, what would you do? A shout could clearly impact on the kicker, but mere gesticulation that the kicker isn't aware of?
(I'll submit it to "You are the Referee....")