The two powerhouses met at Mathoura, with Rochester only needing to halve one rink to finish on top.
Instead, the home side pulled out a performance from the top drawer to clean sweep the three rinks for a 16-75 to 0-33 result.
Mark Quor defeated Brian Trengove 29-8, Peter Holzer recorded a 29-10 victory over Diane Milgate and Christine Taylor edged out Richard Feuk 17-15.
The 84-shot turnaround on the ladder saw Mathoura finish level with Rochester on 134 points, but claim top spot courtesy of superior percentage.
It also meant Moama finished the regular season in third spot, just one point adrift.
The semi-finals will feature return bouts between Echuca and Moama in the first semi-final and Mathoura and Rochester in the second semi-final.
Both matches will be at Echuca Bowls Club.
In Division 2, Mathoura 16-76 proved too strong for Rochester.
The opening week of finals pits Moama against Echuca in the second semi-final and Mathoura against Deniliquin RSL in the first semi-final.
In weekend pennant, Mathoura has two wins and two losses.
Division 1 hosted Tongala and went donw by just one point, 53-54.
Division 2 has better luck away to Echuca, winning 75-47.
Rich River proved too good on their home green, defeating Mathoura 62-52.
Division 4 travelled to meet Lockington and brought home the chocolates, 50-28.
Division 1 finished third on the competition latter and will head into finals, as will Division 4 after finishing fourth.
Division 1 meet Echuca at Rochester this Saturday from 1.30pm.
The Division 4 final will be played at Mathoura against Deniliquin RSL.
Division 2 (5th place) and Division 3 (7th) have concluded their seasons.
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In other club news, congratulations to Mark Quor and Mick Humphreys on winning the Campaspe Men's Pairs.
Good bowling in the games to come.
Congratulations also to Pam Limbrick on making it into the final of the Campaspe Over 60s Women's State Singles against Marilyn Stephenson.
Marulyn claimed the win, 21-11.
Well played to Joan Moss who made it through two rounds of the same competition.
Mathoura has a good number of players in the Campaspe Over 60s Men's Singles.
Michael Humphreys did the best of us and made it into the Semi Final.
R Parry won two games, with other local competitors being D McHarry, D Vallance, M Humphreys and R Cassar.
Well done to Mick and all our other players.