Sydney superstar Lance Franklin enhanced his reputation as a "massive competitor" on Saturday night, fighting on after a knee knock in the opening minutes against Fremantle to boot three important goals.

Franklin was the headline act at Optus Stadium as mystery surrounds his future beyond this season, but the champion forward was forced from the ground early in a crunch game for the Swans. 

After returning and playing a crucial role, particularly through his two goals in a tense third quarter, coach John Longmire was full of admiration for the 36-year-old's fighting effort. 

"There's moments tonight, he just stood up and did what he had to do and imposed himself. He's just such a massive competitor still at 36 to be able to do what he does," Longmire said. 

"He's got a bit of a knock on his knee in the first five minutes, so he just came off at one stage and he just was a bit sore.

"But he got on a bike, he was like on the Tour de France there for a second and had the yellow jersey on and away he went just to get it warm. He bounced back fine. 

"So we'll see how it goes next week but he finished the game really strongly which is good." 

Asked about the prospect of Franklin having played his final game in Perth, Longmire said: "It's not fun for me to go down that path, but I thought he did OK today. I thought he played well."

The most pleasing aspect of the 29-point win for Longmire was the Swans' ability to hit back every time Fremantle looked like mounting a charge, with the Dockers' three unanswered goals either side of half-time their only run of multiple goals for the game. 

"That was a good sign. To be able to hold that momentum and counter punch back," the coach said. 

"We were highly engaged and emotionally tuned into the contest. Straight kicking was a factor in that first half and I thought we played pretty well.

"They obviously rolled the dice in the last quarter where we held up strong. It's always pleasing to come over here and get a win."