Colin Munro's side, Mondiale Auckland Aces, will have to defeat Central Stags (Central Districts) for the second time in just over a week if they are to win the Ford Trophy 50 over competition.
Munro, who was Worcestershire's overseas player in the NatWest T20 Blast last summer, scored 53 when the Aces overcame the Stags by 45 runs in the first preliminary final last weekend to reach the grand final.
But the Stags gave themselves the chance to gain revenge when they reached the grand final themselves by defeating Otago Volts by 49 runs in the third preliminary final yesterday at New Plymouth.
The two teams will now contest the grand final on Sunday, February 1.
In the group stages, it was the Stags who came out on top against the Aces despite another 50 from Munro.
Debutant TC Bruce's 88 off 65 balls was responsible for the Stags yesterday reaching 252 all out in 48.1 overs after winning the toss.
Otago were then dismissed for 203 in 41.5 overs.
Munro will be looking to continue the final form he has shown for Auckland in the competition this winter.
The 27-year-old, who was Worcestershire's second highest scorer in the T20 Blast last summer, had finished the group stages with 297 runs at an average of 59.40 before his half century in the first preliminary final.
Meanwhile Black Caps paceman Mitchell McClenaghan was on the losing side in the seventh ODI with Sri Lanka in Wellington.
McClenaghan, who played for Worcestershire during the second half of last season, returned 0-47 from nine overs as Sri Lanka totalled 287-6 in 50 overs.
The 28-year-old (five not out) figured in a last wicket stand stand of 28 with Kyle Mills as New Zealand were dismissed for 253 in 45.2 overs.
But New Zealand won the series 4-2 with one game abandoned and McClenaghan ended up with 10 wickets from his five matches.