However, the ferocity of their early offerings were impressive, racing out of the blocks to a 11-2 lead as coach Jeff Green unveiled a previously unseen zone defence which provided problems for the Rams.
Lindsay Tait provided his usual playoff intensity with 18 points, 10 rebounds and nine assists, while Corey Webster flashed some distribution skills along with 28 points as the Rangers also made the most of the only Final Four matchup where they aren't at a size disadvantage.
Import centre Terrence Roberts (25 points) was dominant on the offensive glass, with put-back dunks and alley-oops slammed home from all directions as the Rangers lead reached 20.
For the Rams, it was the McKenzie Moore show, with the star guard gamely keeping the Rams in touch with a superb all-around display.
Moore played the whole game, ending with 35 points, seven rebounds, six assists and three steals as he kept the game in the balance, but whenever the Rams made a run the Rangers would answer, eventually killing off the contest.
They will have to deal with a similarly tough opponent in the finale, with 2015 MVP Torrey Craig putting up 21 points, 12 rebounds and four assists as the Saints advanced to their third consecutive final.
In front of a packed Southland arena, the Saints gained revenge for losing the 2015 final to the Sharks, holding on in a frantic finish.
Leading by a small margin throughout, the Sharks kept the contest close right up until the final seconds, with the Saints making key defensive stops to cling on for a deserved victory.
Tai Wesley had 20 points and six rebounds for the Saints, while the Sharks had all five starters in double digits but got only four points off their bench.
Tomorrow's final starts at 7.00pm.
-By Niall Anderson in Invercargill
