Centre-back Cahill said: "When Terry and I have played together for England and Chelsea it has gone really well. He prefers left and I prefer right. The experience he has got has rubbed off on me.
"But I thought our defence was one of the positives from the Euros. This makes my job now a bit harder.
"I couldn't make the impact I wanted to as I did not go, so it is harder now to fight my way back into a starting position.
"That's because of the quality of the players - I've got to fight now to get myself back involved."