Sources have told 7NEWS.com.au Carlton is still chasing a ‘big fish’, their coaching appointment regarded internally as one of the most important decisions in the history of the club.

Carlton’s keeping details of their search a closely-guarded secret.

Watch more on AFL coaching in the video above.

The clue, a ‘big fish’, really suggests that behind the scenes the Blues are still chasing Alastair Clarkson, Ross Lyon or Paul Roos.

It’s understood Hawthorn coach Alastair Clarkson remains number one on the Blues hit list.

Clarkson is contracted to Hawthorn until 2022 and has been very clear he’s fully committed to the Hawks - in particular winning another flag.

It’s unlikely Carlton would make an alternative offer, until they sound out Clarkson one more time at the end of the season.

Alastair Clarkson would be the number one target for Carlton. Credit: AAP

The best coach in the league, Clarkson’s highly unlikely to be swayed by money.

But despite the AFL football department soft cap, Carlton would tempt Clarkson with more than $1.6 million per season for at least 5 years.

Sources estimate Clarkson’s current deal with Hawthorn would be worth around $1.1 million per season.

Sources indicate Carlton is not interested in Ross Lyon, who is close friends with list manager Stephen Silvagni and Blues recruiter Paul Brodie.

If Lyon is the big fish, Carlton is doing a good job passing off.

Fremantle coach Ross Lyon is also a potential option for Carlton. Credit: AAP

Lyon finds himself stuck between a rock and a hard place.

Fremantle currently want Lyon to see out his contract which expires 2020, but aren’t offering new security in the form of an extended deal.

It’s also understood Lyon can’t coach anywhere else next year, unless Fremantle approved it, due to his unique contract.

Trending on 7NEWS.com.au:

Effectively, he’s not allowed to explore other options without Fremantle’s consent.

The other potential ‘big fish’ is Paul Roos, who insisted last weekend Carlton haven’t spoken to him.

A source insists the Blues in fact informally have done just that through a third party, but it’s more likely that would be to sound out his intentions for a potentially lucrative supervisory role, in case Carlton end up going with a less experienced coach.

David Teague has a great coaching record since taking over the Blues from Brendon Bolton. Credit: AAP

Carlton won’t interview interim coach David Teague until the end of the season.

There is a ground swell of popular support for Teague, but it remains highly unlikely Carlton will give the interim coach the permanent job, despite four wins in his first six games in the hot seat.

Port Adelaide assistant Michael Voss interviewed with Carlton last Wednesday.

Brad Scott is yet to declare whether he wants to coach again, but it’s likely he’ll interview with Carlton as soon as next week.

Michael Voss first joined Port Adelaide in 2014, after five seasons as Brisbane coach. Credit: AAP

In the coaching land of ‘big fish’, Clarkson’s a whale, and if bait in the form of $8m and one of the best young lists doesn’t land him, Carlton’s likely to narrow their decision to Voss or Scott.

The obvious difficulty, St Kilda’s also got their line in the water.

And while Worsfold is now safe at Essendon, their remains an off chance Adelaide and Port Adelaide could join in, Ken Hinkley and Don Pyke facing an interesting final 5 rounds.

Tom Browne is an expert AFL contributor for 7NEWS.COM.AU, you can follow him on Twitter here.