The Lions were cleaner with ball in hand and took advantage of costly and regular turnovers from the Eagles.
Lions coach Ronni Hager said the match allowed them to trial a few things.
“We got to run some combinations today (Saturday), so that was fortunate for us,” Hager said.
“Our movement off the bench and through the court worked well, so we were pleased.”
Hager praised her defensive group after the match.
“(Sarah) Szczykulski was fantastic and Nakita (Singe) — they were very solid,” Hager said.
“They got lots of hands to balls and when you turn the ball over you get reward.”
Mansfield coach Simon Dolling knew how hard the task was going to be, but was impressed with his young side's fight.
“Seymour is a really good side,” Dolling said.
“We are a really young side that's just come together this year and are a fairly new group.
“We always knew it was going to be tough up against Seymour, who are obviously well advanced on where we are at, but we thought our girls competed really well.”
The win has the Lions maintaining fifth spot, while Mansfield sits in 11th.
In the round's other matches, Tatura knocked off Rochester 48-40 to move into the competition's top six, Shepparton Swans had a big win over Kyabram, saluting 58-20, Mooroopna defeated Shepparton by 12 goals as it triumphed 47-35 and is now equal on wins with the top-two and Euroa upset Benalla 45-34 to record its second win of the season.
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