Sitting fifth on the Goulburn Valley League ladder, the Lions are teetering on the edge of missing finals with Tatura and Rochester close behind.
With finals out of reach for Osborne's outfit, the departing coach hoped his side could land an upset at Kings Park.
"We've had a really good week on the track at training," he said.
"Everyone's looking forward to getting down to Seymour and putting in a good performance and backing up the match against Tatura.
"We missed a couple of easy shots on goal last week, but there were a lot of positives we can take away from that match.
"Hopefully we can try finish the season off well and knock off the Lions."
Tomorrow's match is also the 50th senior game for teenager Kai Madgwick, which follows Jack Lear recently reaching the milestone.
Osborne said he was rapt for Madgwick, who has been a regular in the senior line-up since his debut aged 16.
"It's great for young 'Madg', I'm really rapt for him, he's been a fantastic player to coach," he said.
"He's been playing senior football since he was 16 years old and he's only going to get better. He has a bright future ahead of him."
Meanwhile, Seymour co-coach Jason Cole was under no illusion of the tough task ahead of his group.
"It's a non-negotiable really," he said.
"It's a make or break game for us, we need to win, it's super important for us.
"Mooroopna had their opportunities last week (against Tatura), they have some great players across the ground.
"We won't be taking them lightly."
Cole said VFL-listed player Jack Murphy could be a chance to play for the Lions tomorrow, as well as Alex Johnston, Jake Anderson and Ben Clifton.
The co-coach said Murphy's addition to the side would bring much-needed zip on the outside.
"We'll look to use him out on the wing (if he plays)," Cole said.
"He gives us plenty of run and carry, which is something we need."
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