United manager Sir Alex Ferguson revealed today that Young was suffering from bruised cartilage and will be out for two to three weeks, but said Rooney was in line to return from a gashed thigh at some stage next week.
On Young, Ferguson said: "Ashley Young has a bruised cartilage that is going to take two or three weeks more. We're taking our time with that one.
"You can easily play and train with it but we are not going down that road.
"We have a lot of experience of these injuries recurring when they come back too quickly.
"We don't want that - we want to give him a full recovery."
Young suffered the injury against Fulham last month, and Ferguson's prognosis would keep the United man out until after the next international break, meaning he will miss England's World Cup qualifiers against San Marino and Poland.
It was suggested earlier this week that Rooney was set to make a rapid return, either in Wednesday's Champions League tie with Galatasaray or this weekend's encounter with Liverpool at Anfield.
Rooney was not involved in midweek and Ferguson has confirmed Sunday is not a possibility either.
However, with a Capital One Cup tie against Newcastle looming on Wednesday, followed by an eye-catching Old Trafford meeting with Tottenham next Saturday, Rooney's absence will not continue for too much longer.
"I know there were reports about Rooney being a possible, but that is not the case," said Ferguson.
"He is not far away. He's doing a lot of great training and has been working hard.
"It's just a matter of getting him into the full football training side of things which he has done part of.
"I think he may be fine for next week."
One man who will definitely feature against Newcastle is Darren Fletcher.
After 10 months out the Scotland skipper finally made his reappearance on Wednesday.
Although Ferguson previously wondered whether Fletcher would ever fully recover from his chronic bowel complaint, progress has been encouraging.
The United boss felt confident enough in Fletcher to hand him an 11-minute run-out against Galatasaray, and next will be a start in the Capital One Cup third-round tie against Alan Pardew's outfit at Old Trafford.
"He made a start on Wednesday which was great and he will certainly play against Newcastle," said Ferguson.
"That is a perfect game for him to start back.
"Then we have the game against Tottenham next Saturday and he possibly could be involved in that, depending on how he does on Wednesday.
"It'll be his first full 90 minutes after 10 months out so it'll be a big night for him."
Ferguson knows Fletcher will never be rid of the condition.
However, the 28-year-old is managing it in a positive manner.
"He's handling the conditions at the moment and he looks fine as we saw the other night," he said.
"It's a matter of hoping the condition stays dormant.
"He's handling his diet well and doing all the right things so hopefully he gets that break he needs."