Metro 14.7 (91) defeated the Croweaters 12.13 (85) in a match that went into extra time as the scores were level at full-time.
As no drawn matches can be played in these championships, the siren did not sound until the next score was registered - a goal from Vic Metro's Ben Sharp. It gave the home side a memorable victory.
But Vic Metro will not know its fate until the second and final division one match on Sunday between Victoria Country and Western Australia.
If Victoria Country defeats Western Australia, then Vic Metro will win this year's title, as the Metro bowled over the Country by 63 points last Sunday.
But if Western Australia defeats Vic Country, then the Sandgropers will win the championship, as they claimed a thrilling victory over Vic Metro at Geelong last Wednesday.
Matt Little booted five goals for Vic Metro in a terrific display, while teammates Jesse W.Smith - the son of former Kangaroos defender Ross, Jarred Moore and Ben Jolley were among the best.
The Croweaters also had plenty of fine performers. Standout draft prospect Ryan Griffen starred - particularly in the second half, while Ben Eckermann, Angus Monfries and Danny Meyer were also key players.
South Australia started the match strongly, booting the first two goals, but a late surge in the opening term from Vic Metro, which produced four in succession, gave the home side a 10-point lead at quarter-time.
Vic Metro made it eight in a row - and five for the quarter - when it slammed on four unanswered goals midway through the second term.
At one stage, Vic Metro led by 40 points, the biggest margin of the match. The Croweaters managed two late goals in the term, but still trailed by 35 points at half-time.
Metro's forwards were on fire during the first half, particularly Little, who booted four goals by the main break. Moore and Jolley were ball-magnets during that period, notching up 29 touches between them.
South Australia produced a great comeback in the third quarter when it booted four goals to one, which reduced the margin to 13 points and set up a fascinating final term.
The last quarter was an absolute beauty. South Australia booted five goals for the quarter - including four in-a-row - to level the scores, but when Sharp nailed his match-winning goal and the Metro's fourth in extra time, the city slickers recorded a brilliant victory.
Victoria Metropolitan: 4.1 9.4 10.5 14.7 (91)
South Australia: 2.3 3.5 7.10 12.13 (85)
Goals: Vic Metro: Little 5, Betts 2, Moore 2, Bain, Herrington, M.Murphy, Sharp, J.W.Smith
South Australia: Grundy 3, Meyer 2, Griffen, Jenner, McLeay, Salter, Saunders, Stribling, Thomson
Best: Vic Metro: Moore, J.W.Smith, Betts, Jolley, Little, Nayna
South Australia: Meyer, Griffen, Hurn, Eckermann, Monfries, McMahon
