After taking down Eaton, Harvey-Brunswick-Leschenault went up against Carey Park in Week Two of the South West Netball Football League's finals series.
Returning to the Eaton Recreation Centre on Sunday, the Panthers secured a 15 to 8 lead at quarter time.
HBL landed 10 goals to six in the second, before trailing by just three at the main break.
Ahead by two at three quarter time, the Lions went on to claim a well-deserved 43 to 35 win.
HBL will clash with minor premiers Bunbury in the decider, held this Saturday in Eaton.
The Masters, Reserves, 18 and Under, and 16 and U grand finals will also take place this weekend.
The ECU Souwest Jets Under-20s have bowed out of this year's West Australian Netball League finals.
Playing at the State Netball Centre on Friday night, East Fremantle Sharks shot 15 to the Jets' 4 in the first quarter.
Sinking 13 goals to 12 in the second, the Jets trailed by 10 at half time.
Led by Goal Shooter Sophie Bell (25 goals) and Goal Attack Matilda Cann (10), the Jets reduced the deficit to three at the final change.
With more attempts on goal in the fourth, East Fremantle held on to win 48 to 36.
Sharks Goal Attack Sarah Burton put up an impressive 21 goals from 24 attempts.