The Tigers trailed at every change of the round nine clash, falling to a 9.4 (58) to 13.11 (89) defeat.
A fast-starting Seymour booted five goals in the first quarter, but Rochester was up to the challenge with four of its own.
The Lions opened a 19-point buffer in the second quarter, however, and an even third term meant the Tigers needed a big lift in the final stanza to steal victory.
No challenge was forthcoming from the Tigers, with one goal not enough to prevent Seymour running away with the game by 31 points.
Mitch Cricelli provided a spark down forward for Rochester with four goals, taking his tally to 26 for the season.
Seymour’s contested ball game proved pivotal, led by Lions’ ruck Seamus Feery, with Lachlan Waite, Josh Alford, and Jack Murphy providing plenty of grunt through the midfield.
Andy Henderson continued his recent run of form with another solid outing for Rochester, while Jacob Atley and Jordan Harper toiled away.
The Tigers fielded four new faces in their round nine squad, courtesy of four injuries sustained in a bruising encounter with Echuca last week.
Defeat at Moon Oval marks a mid-season slide down the GVL table for Rochester, which returned from the bye in first spot.
Solid losses to Echuca and now Seymour in recent weeks have the Tigers in fifth, with crucial match-ups against Euroa next round and Kyabram the week after.
After losing four of its first five games, last season’s surprise packet Seymour (7th) has closed the gap on Rochester and Mooroopna (6th) to two games.