Anderson denies any rift with Manchester United boss Sir Alex Ferguson.
The Brazil midfielder is out for the season after breaking down in the win over West Ham United last month.
"I had no problem with Alex Ferguson, as many people said," Anderson argued to TVI. "I stopped playing for a few weeks because I needed a break to rest my head.
"I felt the ligaments snap in the back of the knee," he recalled.
"The game was only six minutes old, I was feeling well and this happened to me. But this is football and things can happen when you least expect it."
Anderson, 21, will undergo his operation in Oporto and rehabilitate there.
"Knee injuries are always tricky and I want to do a good job of physiotherapy to be 100 percent at the start of next season," he added.