Spurs have started the season well with one defeat in their opening nine games. The north Londoners also boast the best defensive record in the league.
Hazard, a UEFA Cup winner with Spurs in 1984, reckons his former club are firmly on track to win their first title since 1961.
"If I have one regret about the team I played in - which was more than good enough to win a title on two or three occasions - is that we didn't grind out results on days when the flair wasn't quite there," he said.
"You can't play beautifully for 40-odd games in a season and this Spurs side realises that. The desire to stop the opposition scoring in tight games is what title winners are made of.
"It's a case of learning that when things aren't going your way, you can dig in as a unit and do everything that's necessary to get the three points.
"Even Harry Kane is now tackling like a centre-back at times.
"That toughness has come from Mourinho and the different thought processes he's instilling. He's given them a strategy for how to play when things aren't going well - but he's also allowing freedom to attack when Spurs have got the upper hand."
Chelsea, meanwhile, have also lost just once in the top flight this term and have managed six clean sheets in their last eight games.
Hazard joined the Blues after leaving Spurs in 1985 and he believes Frank Lampard's side are yet to hit top gear.
Get the latest transfer news straight into your inbox!
Want to be on the ball with all of the latest football news?
Well then sign up for the brilliant new Daily Star Sport email newsletter!
From the latest transfer news to the agenda-setting stories, get it all in your email inbox.
How do you sign up?
It only takes a matter of seconds.
Simply type your email address into the box at the top of this article and hit 'subscribe'.
And that's it, job done. You'll receive an email with all of the top news stories every single morning.
You can find out more information on our email newsletter on this link here.
"Everyone already regards Chelsea as a good side, but the likes of Timo Werner and Kai Havertz will adapt even more to the English game and the team," he added.
"As time passes they'll get even better and their rivals - like Spurs - will be aware of that.
"Chelsea are a top club and these days demand to be competing near the top of the table. There will be no surprises if they mount a serious title challenge as well."