Manchester City football development executive Patrick Vieira believes Manchester United's decision to recall Paul Scholes to the first-team picture in January is a sign that there is "a little bit of weakness" in the Premier League leaders' squad.
Scholes, 37, announced his retirement at the end of last season after United claimed their 19th league title, but made a dramatic U-turn in January - returning to the first-team and playing in 13 of the Red Devils' past 15 games.
The veteran midfielder has plugged the midfield gap left by long-term absentees Darren Fletcher and Anderson, and United have won all seven Premier League games he has started.
Vieira, who played against Scholes for Arsenal and City before retiring himself at the end of last season, admitted he has been impressed with the former England international's impact, but insists the need to call on a 37-year-old is proof that United lack strength in depth.
"Paul Scholes is a player that I really love and admire, one of the best English players of the last few years, and seeing him come back is good for him and for United," Vieira said.
"But for him to come back just shows a little bit of weakness in United, because they had to bring a player back who was 37.
"I think it shows that, in the next few years, it will be really difficult for United to cope with other teams because, with all the respect I have for Scholes, him coming back shows that they don't have talent in there to replace him.
"When you see United losing young players like Ravel Morrison and maybe Paul Pogba, they should be really worried because that wouldn't have happened in the past."