FREMANTLE defender Michael Johnson made a pre-season pledge to repay his teammates for a lacklustre two seasons, and he made the perfect start against Geelong in round one.

The 27-year-old, who is returning to the backline under new coach Ross Lyon, had 24 disposals and a game-high five rebound 50s to play a crucial role in Fremantle's dramatic four-point win over the reigning premiers.

It was the perfect response to a forgettable 2011 season for Johnson and reward for a strong pre-season that has seen the creative backman shed five kilograms and cut his skinfolds significantly.

"What I've worked on over the pre-season is slowly paying off, so hopefully I can keep building," Johnson said. 

"That's one game out of the way, so hopefully I can get better. It's a long season ahead."

Fremantle's backline, which included St Kilda recruit Zac Dawson for the first time on Saturday night, was under enormous pressure at stages against the Cats, particularly in a frantic last quarter.

Geelong won the inside-50 count 54-41 for the match, but Johnson proved his move back into defence could be a masterstroke, blunting a number of Geelong entries when playing as a loose man.  

"The whole backline really stood up, and we were under pressure a few times there," he said.

"We stuck in there and did what we had to do, especially in that last quarter when they kept on coming at us.

"We stayed strong and next time we have a close game we'll back ourselves, because we've done it already."

Johnson said the over-riding emotion on Saturday night was relief after a long build-up to round one and a demanding preparation under Lyon.

He said the coach had instilled structure and discipline in the group, with both traits evident against the Cats, apart from a lapse in the second quarter that saw the visitors boot five goals to two. 

"It did drop away at stages of the game, but we worked on it in the last quarter and it just pays off when you play to your structure and what you've trained for," he said.

"We've worked hard over the pre-season and it's paid off. We move on now and concentrate on Sydney.

"It's just one game, one tick, but we've got a long way to go."

Nathan Schmook covers Fremantle news for AFL.com.au. Follow him on Twitter: @AFL_Nathan