Scores were level at three-quarter time but Duffy's fourth and a late major to Gemma Houghton sealed the 6.8 (44) to 4.4 (28) win in front of 5509 fans.

Duffy ended with 4.0 from 12 disposals, while Houghton (17 disposals, one goal), Kiara Bowers (22 possessions, 14 tackles) and debutant Roxanne Roux also impressed.

Geelong were well led by Olivia Purcell (27 disposals, seven clearances), Julia Crockett-Grills (23 possessions), and Rebecca Webster.

It was a deserved win by Fremantle, who won the inside 50m count 47-13.

"We would have liked it to be easier for our dominance but just really happy to get the win in the end," Dockers coach Trent Cooper said.

"I was really rapt with Sabreena's pressure when the ball was on the ground. And she competed in the air so often.

"I didn't realise she kicked four goals. It's just the way the footy gods work sometimes; you get rewarded for your effort."

The Dockers suffered a blow when midfielder Stephanie Cain copped a game-ending knee injury in the opening minutes.

Cooper is optimistic it isn't an anterior cruciate ligament tear.

Fremantle dominated early but the Cats fought back to take a two-point quarter time lead.

Both teams booted two goals in an entertaining second term featuring several brilliant moments.

Geelong forward Richelle Cranston made the most of a fast break by sprinting forward, handballing to herself to shake off Evangeline Gooch and kicking truly from 25m.

Dockers debutant Roux produced her own highlight with a clever snap from 30m.

Fremantle led by one point at halftime, despite dominating the inside 50s 24-8 and the theme continued in the third term as Geelong continued to hold firm in defence.

The Dockers blew a series of golden chances early in the final term, with Roux and Houghton booting two points apiece.

But when Duffy bagged her fourth and Houghton finally found her range, it was game over.

"We were pleased with our first three quarters. We just need to tidy up our composure under pressure and our ball handling to make sure we can stay in the game for longer," Geelong coach Paul Hood said.

Australian Associated Press