Leeds boss Dennis Wise admits he didn't want to sell veteran winger Eddie Lewis to Derby County.
"He's been a good pro, he's done very well for us and I'm chuffed to bits he has got an opportunity like this."
Rams boss Billy Davies has worked with Lewis before when the two were together at Preston.
"The left side of midfield is an area we have targeted for improvement and Eddie has a wonderful left foot," said Davies. "His delivery from wide areas and set-pieces will provide an excellent platform for our attacking play."