The England defender has been impressed with the new signing after the Belgian international inspired the Blues' late comeback against Reading at Stamford Bridge
The 21-year-old was in imperious form against Wigan at the weekend and continued from where he left off, playing a key part in three of the four goals the Blues scored.
And Cahill, who felt he was at fault for Reading's opener, singled out the 32 million-pound man after inspiring the comeback.
"I thought [Hazard] was absolutely fantastic tonight," Cahill told Sky Sports News.
"The other day against Wigan obviously he was great again but tonight I thought he was special."
Cahill grabbed the equalizing goal when the Blues were 2-1 down, but also feels he took a portion of the blame for Reading's opener as Pavel Pogrebnyak beat him to head home.
"It was a superb cross and a great header, but I've got to be tighter," Cahill stated.
"It happened again about five or 10 minutes later and I got across, I should have done that first time but I'll learn from that. I thought we kept plugging away even though we were 2-1 down and there were some great performances out there.
Cahill missed Euro 2012 after sustaining a fractured jaw in the 1-0 friendly win over Belgium at Wembley, and also missed out on Saturday's opener at the expense of David Luiz. The Brazilian was unavailable for selection tonight due to a knee injury, and Cahill insists that everyone will have a part to play this year, much like last season.
He continued: "I think we'll all play our part, you saw that towards the end of last season. The rotation of the squad, there will be players in and out."