Striker Jason Hayne had earlier scored twice for the Oceania champions from New Zealand, who won two of their three matches in the tournament.
Auckland went in front just before the half hour when Hayne beat the offside trap to race clear, chest a high ball down as he rounded Mazembe's reserve keeper Aime Bakula outside the box and steer it home.
Mazembe goalkeeper Muteba Kidiaba had been sent off five minutes earlier for handball as the last man in defence when striker Daniel Koprivcic chased a long ball out of defence having jumped the offside trap.
The African champions, who had done most of the attacking in the first half, turned the score round with better finishing in the second, scoring two fine goals.
Striker Ngandu Kasongo found the top corner of Paul Gothard's net with a shot from outside the box to equalise for the side from the Democratic Republic of Congo on the hour.
Seven minutes later, left back Kilitcho Kasusula, who had earlier had a good chance well saved by Gothard, gave the keeper no chance when he raced into the box to slam into the net from captain Mabi Mputu's brilliant backheel.
Auckland pulled level with 18 minutes to go when Bakula blocked substitute Grant Young's effort and Hayne blasted in the rebound from the edge of the box.
Substitute Dioko Kaluyituka had two good chances to win the match for Mazembe in the final three minutes but shot wide with only the keeper to beat.
With the end of four minutes of stoppage time approaching, Auckland, who made better use of their 37 percent share of possession, broke down the left and Van Steeden steered the winning goal into the bottom near corner.
