"And that is probably the most convincing win we have had all season which puts a bit of confidence in the boys for the semis."
Greerton batted first on Saturday and were removed for 124 runs, which Central chased down with six wickets to spare.
Central bowler Andrew Gibbs took five wickets for 16 runs during the game, and long-time Central club member Mark Chapman anchored his side's victory with an unbeaten 49.
"I think [Greerton] came out swinging thinking they would put 300 on the board and even when we took a few wickets they were still aggressive and did not play to the situation," Trembath said. "And we got rewarded for it."
By finishing in the top two on the ladder, it means Central get a second life in the playoffs.
The winner of the Central versus Cadets semifinal will go straight to the final while the loser will play the winner of the other semifinal, between the third and fourth-placed teams Mount Maunganui and Te Puke.
Te Puke leap-frogged Greerton on Saturday to make the semifinals, after beating the Bay of Plenty Indians (Rotorua). Te Puke batted first at the Te Puke Domain and were removed by the Indians for 154.
Rohan Gosai and Jayvant Dhanjee both grabbed four-wicket bags for the visitors.
The Te Puke bowling attack tore through the opposition batsmen though to dismiss them for 71, to claim the last post-section place.
In the other matches, Cadets grabbed second place on the ladder by beating arch-rivals Mount Maunganui at Blake Park, and Tauranga Boys' College cruised to a big win over Whakatane United in the Eastern Bay of Plenty.
- Williams Cup results on Saturday:
Greerton 124 (Tom MacRury 29; Andrew Gibbs 5/16, Mark Chapman 2/19, Jason Trembath 2/26) lost to Central 125/4 (M Chapman 49no, Johnny Barrow 25; Brett Hampton 3/47)
Te Puke 154 (Devon Bell 49, Tai Bridgman-Raison 38; Rohan Gosai 4/16, Jayvant Dhanjee 4/23) defeated BOP Indians 71 (Ollie Smithson 3/21, Justin Scott 2/7)
Whakatane United 166 (Tom Yates 53, Matt Davies 23) lost to Tauranga Boys' College 167/1 (Mark Orchard 70no, Sean Dykes 48no)
Cadets 180 (Sean Davey 51, Donovan Deeble 36; Luke Tatley 3/20, Dale Swan 2/26) defeated Mount Maunganui 114 (Dan Hill 33; D Deeble 4/16, Ben Christensen 4/35)
- Points table (final):
Central 36, Cadets 36, Mount Maunganui 30, Te Puke 24, Greerton 24, BOP Indians 9, Tauranga Boys' College 9, Whakatane United 0.