The Scotland midfielder has fought back from the career-threatening illness that has sidelined him from first-team action since last November.
He played two games for United reserves recently and manager Alex Ferguson indicated last week he would be included in the club’s Champions League plans.
Fletcher, who has been plagued by a chronic bowel condition, was due to train with Scotland this week ahead of their opening World Cup qualifiers.
Ferguson said last week: “Darren’s back to his normal weight from two or three years ago. It’s a case of wait and see.” He added: “But Darren comes into the 25-man squad quite easily, without me having to leave others out because we have a number of players who we don’t need to register because of the time they’ve spent with us as an academy player. That’s an advantage.
“He’s training well every day and played really well the other night for the under-21s.”
Kolo Toure meanwhile was left in Champions League limbo after being left out of Manchester City’s squad for the group stage of the competition.
And the defender also failed to complete a move to Galatasaray in time to be named among their 25-man submission to UEFA.
Toure has reportedly been in talks with the Turkish giants about a move ahead of their country’s transfer deadline tonight. But the 31-year-old, who has just a year left on his City contract, could now see his value fall due to being ineligible for Europe’s elite club competition.
City were also unable to find a place for new goalkeeper Richard Wright in their squad.
Elsewhere Florent Malouda could be the latest player to leave Chelsea after he was left out of their squad for their Champions League group-stage.
This opens up the prospect of Malouda being sold or loaned out in the near future, either way effectively ending his five-year Stamford Bridge career, with less than a year remaining on his contract.
The 32-year-old, linked with a return to former club Lyon ahead of last night’s midnight transfer deadline in France, has not featured at all in any of Chelsea’s matchday squads this season and has been heavily touted for a move away all summer.
He was omitted from the 29-man party the Blues submitted to UEFA ahead of their defence of their European crown and although he was named in the squad for the first half of the Barclays Premier League season, that may not prevent his departure.
A transfer to Brazilian giants Santos reportedly collapsed earlier this summer due to wage demands. Malouda has been at Chelsea for five years. Veteran keeper Hilario was also omitted from the Champions League squad announced, although he too was in the Premier League submission.