The Hammers boss, whose side lost at home to Stoke on Saturday, has played down the east London club's chances of bringing in new faces before the window shuts on Monday
The Hammers have been linked with a move for forward reinforcements due to Andy Carroll’s heel injury, which has kept the England man out of action so far this season, while Ricardo Vaz Te has asked to leave the club.
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He said: "When you’ve got to overlap one with another coming in to create the finances for the one coming in then they almost have to sign at the same time.
"I can’t let that player sign for an opposition side until I know definitely that the player I’m bringing is going to sign for us.
"Until he has put his signature on the paper he hasn’t signed for us even if he is in the building. It makes life extremely difficult for us, but it is also difficult to find players of the quality to play at this level.
"A player we bring in we might need or want to play in the first game at Southampton and if we’re going to get anyone they’ll be from outside of this league."