The Brazil midfielder was handed a late cameo by coach Jose Mourinho and pulled up in good shape.
"It's a great joy to be on a football field again," said Kaka. "I've had very bad moments in recent months, not knowing if I would even play again.
"But I think I'm now over this injury. I hope to play at a high level again.
"I have not done anything yet in Spain. For me it is a great challenge, and I want to play at a high level."
He added: "I have yet to earn my place. The team is playing well ..."