Gary Neville has claimed that Louis van Gaal and chief executive Ed Woodward will face "massive two weeks" as Manchester United look to retain the players and make new additions to the squad.
David de Gea's future at the club remains uncertain as the Spain international has been heavily linked with a move to Real Madrid and the Dutchman is unhappy with his goalkeeper's situation.
In the attacking division, Red Devils have the services of Wayne Rooney and Javier Hernandez as the two recognised strikers, along with youngster James Wilson in the squad. The transfer deadline day closes on 1 September and the Old Trafford favourite believes United could be in trouble if they fail to strengthen the squad before the window shuts.
"It's a massive two weeks for Manchester United in terms of holding on to players and trying to strengthen where they can," Neville told Sky Sports.
"They could find themselves in a position where they've only got one centre-forward and potentially not the best goalkeeper if De Gea moves to Real Madrid.
"They could also have a problem at centre-back if they get an injury - Phil Jones is out at the moment - so they could need another centre-back. That's three main areas of the pitch," the Old Trafford legend said.
"Centre-midfield was the position where United needed to improve in the last three or four years and they are actually OK in there now.
"But now they look weak up front with just Wayne Rooney and Javier Hernandez. At the back too, if they get another injury, they would look weak there," he added.
Meanwhile, Woodward flew to Cataluniya to seal a deal with Barcelona for Pedro. The forward could be on his way to Old Trafford and sign for United by the end of this week, according to The Times.
Summer signing Sergio Romero started in the first two matches ahead of De Gea and the Argentine international has kept two clean sheets in the process. Should the former Atletico Madrid 'keeper return to Spain, United already have a readymade replacement.