Fyfe twice dislocated his troublesome left shoulder earlier this year before being sent in for surgery.
Fremantle's midfield has struggled to cope at times without the classy onballer, but Lyon said the club was taking a careful approach with Fyfe given his history of shoulder problems.
"Nat Fyfe is absolutely tearing the house down with work, but he'll be [returning in] round 18, if that," Lyon said.
On paper, Freo's next three games are all very winnable - Melbourne (away) and GWS (home) before tackling Port Adelaide at AAMI Stadium in round 18.
Defender Zac Dawson, who has missed the past three games with a knee injury, is a chance to return for Saturday's clash with Melbourne at Etihad Stadium.
And fellow backman Antoni Grover will be assessed this week after copping an accidental elbow to the head in a mid-air collision during Sunday's 38-point win over the Western Bulldogs.
But Lyon felt his team was still too handball-happy at times, and needed to become more direct to match it with the top sides in the competition.
Skipper Matthew Pavlich, who booted six goals against the Bulldogs, said his team's more direct approach in the game-defining third quarter was the blueprint for future success.
"I think it gives the guys a really clear path about what is success, and how we should play," Pavlich said.
"We're still not perfect, I think that's the main message.
"We've still got a lot to work on, but when we're playing our best it does mean we are penetrating a bit more."
