Shannon Seebohm has backed Townsville Fire's reserve point guard Lucy Olsen to be the x-factor in their WNBL grand final series against the Perth Lynx.

The Fire punched their ticket to the league's championship series on Sunday after beating the Southside Melbourne Flyers in a thrilling 84-74 encounter.

But Townsville won't be celebrating as they'll instead shift their focus to the Lynx and the best-of-three tie beginning on Thursday.

Seebohm believes he already knows who is going to play a big part and instead of pointing to the red-hot Alicia Froling or MVP contender Courtney Woods, he's supporting his WNBA import Olsen.

The 22-year-old has spent much of the season coming off the bench, with the coach opting to start young gun Abbey Ellis instead.

"She's going to be the x-factor for us. She's going to have a big part to play in this series," Seebohm said after Sunday's game.

"She's a big game player coming from Iowa who's played in front of massive crowds and all these things in college. She's going to be ready for this moment.

"Her defence has improved a lot as this season's gone on, and she was extremely tough out there for us today and in game one."

The coach also expects Olsen to shine offensively despite the 22-year-old registering two points and five assists on Sunday.

Regardless, the Fire are preparing for a dogfight against the Lynx.

Their tussles have been dramatic, with the most recent affair ending in controversy after Froling allegedly called Han Xu a "crybaby" after her reaction to an elbow to the nose.

Seebohm declared there was a strong rivalry between both sides as the grand final series would be their fourth consecutive post-season meeting.

"They've got a heck of a team. I'm assuming, they're the favourites going in," he said.

"We need to get to the drawing board and figure out what it is that we're going to actually do against them to try and slow down their offence."