The Northern Ireland forward was soon withdrawn but not before spinning on the edge of the box to fire a shot wide, Gregg Wylde sent on for a final 10 minutes in which Rangers held firm.
They threatened the increasingly anxious Spurs defence with every set-piece, and the second goal arrived when a loose ball was not cleared and Johnson was the fastest to react, spinning on the edge of the six-yard box to poach his fourth league goal of the season.