Emiliano Tade gave his side another lead before the second red card, leaving Auckland to cash in against an over-matched opposition. Exposito snatched a second, substitute Darren White scored a brace and centre-back Mario Bilen got in on the action to all but seal Auckland's place in the May 19 final.
Waitakere are in a good position to meet City in the one-off match at Mt Smart Stadium, securing two away goals against Amicale to take charge of the tie. It would be a fitting finale to the season for the two rivals to clash for a spot at the Club World Cup in Morocco and the US$500,000 pay day that comes with it, giving Auckland a chance for revenge after Waitakere won the ASB Premiership in an epic extra-time final in March.
But Auckland coach Ramon Tribulietx wasn't getting ahead of himself, despite Ba needing a miracle to force their way back into the contest.
"We're not going to relax,'' he said. "We would be making a big mistake if we thought it was already done. There's still 90 minutes to be played and anything can happen - we still have to make sure that we compete.''
Ba were competing well in the first half today, looking menacing on the break and refusing to let Auckland relax in possession. The 3000 fans at Kiwitea St consisted of a sizeable Fijian contingent and they would have been impressed by their side, until Avinesh Suwamy's X-rated tackle on Takuya Iwata.
Auckland began to make the most of the numerical advantage in the second spell and the lively Tade notched a well-earned goal, before Meli Codro matched his teammate's brain explosion. Having completed an innocuous challenge on Exposito, Codro trod on the striker's back right under the nose of Tahitian referee Norbert Hauata, completely transforming the tie.
"For them, it was really hard to play with nine men,'' Exposito said. "They mentally switched off a bit, which was understandable.''
Auckland stayed right on task and could have easily scored 10, such was their dominance. But six will almost certainly prove more than enough.
Auckland City 6 (Exposito 31, 73, Tade 63, White 80, 89, Bilen 86)
Ba 1 (Manuca 34)
HT: 1-1