Louis van Gaal has said it is possible Manchester United could make signings in the January window.
United have been linked with a host of players as they look to kick-start their season after a disappointing end to 2015, when they went six Premier League games without a win and exited the Champions League.
Van Gaal said he did not favour doing business in the winter window but was willing to make a move if the right players were to become available.
Writing in his programme notes ahead of the Sheffield United game in the FA Cup, Van Gaal said: "January brings the opening of the transfer window and, as I have already seen, we have been linked to a host of players.
"I don't see January as the ideal time to do business as the players cannot then have the preseason that I feel they need to be integrated into the squad, both on and off the pitch.
"However, if I and the coaches feel that something can be done to improve the current squad then that is something we will look at if the opportunity does arise."
United have been linked with a host of players including Watford's Odion Ighalo, Real Madrid's Gareth Bale and Southampton's Sadio Mane, although they all appear likely to stay put until the summer at least.
Lazio, though, have said they will evaluate offers for attacking midfielder Felipe Anderson.