The former Dundee United star has turned down a contract offer with the Rams and is believed to favour a move to the States.
The Scottish forward's current deal expires at the end of the season and, with Colorado Rapids reportedly interested in the striker's signature, he could soon be on his way.
Russell, who joined Derby from Dundee United in 2013, has made 203 appearances for the club, scoring 34 goals in the process. He has featured 25 times this season, bagging five goals along the way, and will be missed by Gary Rowett should he seal a move away.
"I think his wish is to pursue a chance to play in the MLS," the Derby boss said. "He's turned down those contract offers. We'll have to look at that situation."
With Derby set to lose Russell, and compatriot Chris Martin being linked with a loan move away to Sunderland, Rowett confirmed that it is likely the club will look to add a new forward option before the end of the window.
The Rams have previously been linked with a move for West Bromwich Albion's James McLean, although the Baggies are not looking to let the Irishman leave this month.
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