Cahill was on the losing end of a 2-0 result against his old club.
He said at the final whistle: "It was very strange to come back here. It was always going to be a bit emotional and a bit weird. Thank you to the fans for the reception, that was terrific. To spend so much of my career and life as a footballer here, and the memories I've got, that's life as a footballer, you move on.
"We've come up against a very good team in very good form so it was difficult today. We defended very well as a team in the first half. The onus is on them to be on the front foot but we soaked it up and defended well. The first goal was a blow and luck went their way.
"We started the season very well and that's an understatement. We know we've got the ability to go on and finish in a decent place. We're looking to finish in the top half. You have to have goals and ambitions. This run is tough, but it's time for us to really knuckle down and try and win some points.
"For a fan of Chelsea it's so exciting for the young lads to have these opportunities... It was very tough today. We played well but the quality's there. The more experience they get the better they'll be for it."