Roberto Martinez says any transfer activity ahead of Friday's deadline is likely to depend on the future of John Heitinga.
The Blues boss revealed that Heitinga, 30, was this week given permission to speak to two clubs.
And while no agreements have yet been reached, Martinez believes the defender could still depart Goodison Park.
"Anything between now and the end of the window will focus on how Johnny's situation develops," said Martinez.
"He was given permission to have talks with a couple of clubs and over the next 48 hours we will find out what the final outcome is."
Martinez had previously stated he was willing to allow Heitinga to leave in order to allow the Dutch international to fulfil his desire for regular first-team football in the build-up to this summer's World Cup.
The Spaniard, however, remains a big admirer of the defender's talents and admitted he would be happy if Heitinga remained on Merseyside.
He said: "It is very important that in this window we try to find the right solution for him. But if that solution is to stay at Everton, he is somebody we didn't want to lose in the first place."
Martinez has already acquired winger Aiden McGeady during the current window, while loanee forward Lacina Traore was unveiled to the media on Thursday morning.
"If I'm honest with you, bringing Aiden and Lacina in were the big priorities for me," said Martinez. "My focus now is on bringing the players back that we've already got.
"We've been affected by too many injuries and we are working on getting all those players back. For me, football is not about numbers, it's about quality.
"Every window we will try to be as strong as we can be. We haven't lost any of our top performers and we have added two good additions, so we are stronger. I'm really pleased with Aiden and Lacina coming in.
"What we want is to get all the players back from injury because when we have everybody fit and available we have very strong options.”