Rooney was left with blood pouring out of a deep thigh wound after being caught in the thigh by Hugo Rodallega's boot studs during United's 3-2 win over Fulham at Old Trafford last month.
The England star was rushed to hospital where he discovered the gash was close to severing an artery, which could have had severe repercussions.
In the circumstances, Rooney knows he is fortunate that the injury will only keep him out of action for four week and, quoted in several national newspapers, he said: "I was quite lucky it didn't cut my muscle.
"I was told it was just one millimetre away from severing an artery. It could have been a lot worse, so thank God for that. I could have been in serious trouble.
"The doctors said a lot of players could have fainted. They tried to cover it up from me in the dressing room and put something in it to stop it being infected, but I told them I wanted to watch.
"Thankfully, their prompt action prevented serious and possible lasting damage."
Rooney's injury has stopped him developing a partnership with new signing Robin van Persie who, in the former Everton striker's absence, scored a match-winning hat-trick at Southampton last weekend.
Some pundits have suggested van Persie's arrival spells the end for Rooney at Old Trafford, but he is confident of striking up a formidable partnership with his new team-mate.
"You can't assume you're going to play but I've always worked very hard to make sure the manager has got to play me," Rooney said.
"It's great for us now. I'm looking forward to getting back in the team and trying to forge an understanding with Robin.
"Let's be honest, where else can you go from this football club? It's probably the biggest in the world."