Emerging key defender Matthew Watson has had some good news in the wake of his season-ending foot injury, re-signing with Carlton to the end of 2015.

Watson has also received a positive preliminary prognosis on the injury he suffered in the Blues' loss to the Western Bulldogs on Saturday, with Carlton confident he will not need surgery.

The 21-year-old told AFL.com.au on Monday scans had revealed a hairline fracture at the top of his left foot.

Watson will be assessed by a specialist on Tuesday but the Blues believe his foot will heal naturally in time for the start of 2014 pre-season training.

"I went for a kick and I followed through and hit one of the Bulldogs players in his foot or his shin," Watson said.

"The 'doc' thought it was ligament damage, got a few scans and it showed a hairline fracture at the top of my foot.

"I'll be in a (moon) boot for the next three to four weeks and then I'll be back for pre-season, don't worry about that.

"I've got a bit of time off after the season. I'm going to rest up and let it strengthen up before we get back into training in November."

Watson was due to come out of contract at the end of this season, but Carlton re-signed him for the next two years following his promising form over the past five rounds.

At 195cm and 100kg, Watson shapes as one of the key planks of Carlton's 'spine' over the next decade. 

The key defender was the Blues' first selection at the 2010 national draft at No.18 overall, but struggled for senior opportunities in the first half of 2013.

Watson earned a recall in round 16 after working hard on the balance of defence and attack in his game, and on his acceleration off the mark.

"I got caught on the lead a few times by my opponent and it was just a matter of doing a lot of work on my speed (and) acceleration during training," Watson said.

"That's improved and it's helped me get a game."

Significantly, Watson's ability to hold down a key defensive post before his injury allowed Carlton to play fellow tall Lachie Henderson in attack.

"It was good to get the confidence up, get a few kicks. I was pretty happy to string a few games together," Watson said.

"At the moment I'm playing my best footy in defence. We've got a good group down there … and if we have all the backmen playing well and 'Hendo' in great form kicking a few goals that gives us a strong target down forward.

"So I've just got to keep playing well (next year), so we can keep Hendo up in the forward line and keep getting wins."

A booming left-foot kick, Watson has played 16 games for the Blues.