Cahill claims the Serb has made an instant impact since returning to the club he left for Benfica three years ago.
"He played against Stoke and he brought strength and power in the middle of the field and he did the same against City," said Cahill.
"He breaks play up, and he can drive forward with it as well - he's got a lovely left foot, great passing - he looks like the all-round player.
"He's played two games for us, and done really well. Hopefully that'll continue - he's settled in very fast."
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball