Ronaldo ahead of schedule for return
It had been feared Ronaldo would be missing for at least three months after an operation on his right ankle in Amsterdam on July 7.
Ronaldo, 23, said: "I am feeling fine. I am feeling really good and my recovery is going well.
"I am more than happy with my progress and I hope to be back playing for United by the end of September - that is my target and it is a realistic one.
"It has been frustrating to miss the start of the Premier League season but I am pleased with my rehabilitation and, hopefully, I'll be ready soon."