Rooney suffered a deep wound in his leg after being caught by Fulham's Hugo Rodallega, keeping him out for four weeks.
However, the 26-year-old revealed that the cut missed his artery by a millimetre, and that the injury could have been much worse had it hit it.
"I was quite lucky, to be honest. It somehow didn't hit my muscle. It was a millimetre away from my artery so it could have been a lot worse than it was. I have to thank God I am quite fortunate," Rooney told Sky Sports News.
"The doctor said a lot of players would have fainted. They tried to cover it up in the dressing room when they were treating it to stop it becoming infected, but I told them I wanted to see it.
"It is feeling good at the minute and is healing quite well, but it is basically down to the doctor. You have to be careful and I don't want to come back too soon because I could get a bang on it and it would open up again. We said at the time there was a four-week scale and that would be the case, I imagine."
Rooney could be back in time to face Liverpool on September 23.