Christchurch struck first, when Blake Weston was left alone to head home from a corner.
Auckland City responded four minutes later with a trademark play that saw the ball travel wide, back and wide again as the Navy Blues moved forward as a unit.
Cam Howieson made the decisive pass and run into the box to take the return and cross for Reid Drake to finish at the far post.
In the 40th minute, City played through the middle for Dylan Manickum to set up a play on the edge of the area, for Howieson to rifle home a well-placed shot.
That gave City a 2-1 lead at half-time.
Two critical incidents, both leading to penalties, defined the opening segment of the second half.
Christchurch United were awarded a penalty straight after the break but Eddie Wilkinson struck it against the post.
On the hour mark, United’s Weston handled in the box, giving City a penalty which Angus Kilkolly had no trouble putting away.
In the 75th minute, Christchurch supporters were given hope when a high press paid off and the home side won possession with City on the back-pedal.
Daniel Maclennan was able to tap the ball in and it was 3-2.
The win took City to the top of the table.