A WEEK proved to be an awfully long time in the career of star Hawthorn forward Lance Franklin.

When he was carried from the MCG after suffering a knee injury in the Hawks' qualifying final loss to Geelong, it seemed certain he would miss the rest of the season.

It was even feared that he might also have been sidelined for much of 2012.

Yet seven days later, Franklin booted a game-high four goals in Hawthorn's 36-point win over the Sydney Swans in Friday’s second semi-final.

"He'd convinced himself he was going to play as soon as he had the scan that said all the structures in his knee were fine," Hawks coach Alastair Clarkson said after his team scored its first victory in a final since it won the 2008 premiership.

"We weren’t so certain because … the mechanism of him landing looked very awkward.

"It didn't look too promising there for a while, but he knew as early as Saturday that he was a chance to play.

"It took until Thursday for him to convince us, but our doctors and specialists that looked after him throughout the course of the week … were just outstanding.

"He had to do whole series of tests nearly every day, in a sense, to just see how it was coming along."

Franklin didn't fully test the knee until he was put through his paces by Clarkson and the club's medical staff on Thursday morning.

"I looked at him there … and I thought he was going to be right to play," Clarkson explained.

"He wasn't inhibited at all by the leg.

"Not that many people put jabs into knees, but under no circumstances were we going to put a needle into him.

"If he couldn't train, and do what we wanted him to do yesterday morning, then there was no way that he was going to be able to play.

"But he'd decided on Saturday that he was going to play this week, and full credit to the lad. His preparation for this game was extraordinary."

Franklin looked somewhat troubled by the knee early in the game against the Swans but was moving freely by the end of the contest, and now looks certain to play a key role in Hawthorn's blockbuster preliminary final with Collingwood next Friday.

With Franklin fit and firing, the Hawks rate their chances of advancing to the big one.

"We all start even now," Clarkson said.

"As good Geelong and all sides have been throughout the course of the year, everyone hits the starting blocks even next week.

"We know that Collingwood have been in outstanding form, but at the start of the game she's zero-zero, and we'll give it a crack."

Reflecting on the win over the Swans, Clarkson praised John Longmire's team for fighting the game out.

Down by 46 points early in the third quarter, the Swans narrowed the margin the 18 points at the final change before the Hawks pulled away again.

"It was a tough game," Clarkson said.

"We started the game really well. To restrict the Swans to only a point at quarter time was a terrific effort.

"That got the game in our control. But when you're playing in the last three weeks of the season you expect that you're going to have a fight at some point in time, and that certainly came in the third quarter.

"That 300-gamer [Adam Goodes] got hold of us for a while. He's just an outstanding player.

"We'd been able to keep him in reasonable check in the first half, but he just exploded.

"Luckily, at three quarter-time we were able to rally the troops a bit and they responded in the right manner in the last quarter, so it was a great effort."