Derby will assess goalkeeper Lee Grant's fitness before deciding whether or not to further extend Jack Butland's loan.
Celtic claim a fee was agreed with Manchester City for John Guidetti prior to them taking the striker on loan.
The Latics have already signed left-backs Andrew Taylor and Aaron Taylor-Sinclair so far this summer.
Rosler has now revealed that he is waiting to hear if two more of his targets will be joining his squad for their training camp in Germany next week.
However, the 45-year-old has not named the players that he wants to sign in order to reinforce his squad for the 2014/15 campaign, in which the 2013 FA Cup winners will be aiming for Premier League promotion.
"The chairman remains very supportive of what we’re doing and hopefully we will be able to present a couple of new signings before we fly out to Germany," he told the Wigan Evening Post.
"We have already signed two players, we have bids in for another two players, so the ball is rolling.
"Unfortunately it is not solely dependent on us – you also have to consider the other club, the player and also the agent.
"To get everything together under one umbrella takes time, and that is what we have been dealing with.
"We are always looking for new faces. But sometimes it happens earlier than you thought, and sometimes it can take a little longer and you have to wait."