Sky Sports understands a number of clubs are tracking highly-rated Carlisle United midfielder Brad Potts.
Sheffield United are planning to send Andy Butler back out on loan after seeing an agreement with Walsall collapse.
The 27-year-old, who joined Oldham on a season-long loan in the summer, is now a free agent.
His contract with Derby was due to expire in the summer and his loan spell at Boundary Park has also been ended early so his Rams deal could be terminated.
Croft arrived at Pride Park on a free transfer from Norwich City in the summer of 2009 but gradually fell down the pecking order and made only five starts and five further substitute appearances last season.
He also spent the second half of the 2011/12 campaign on loan at St Johnstone.
The former Manchester City trainee and England U20 international made 31 appearances in total for County.