Burton have signed midfielder Adam Bolder on a two-year contract.
The 29-year-old, who played with Brewers boss Paul Peschisolido at Derby, has been training with the League Two club.
Bolder has been released from his contract at Millwall to enable him to sign for Burton, subject to Football League ratification.
"This is a huge piece in my jigsaw for this coming season," Peschisolido told the club's official website.
"I am absolutely delighted to get someone of the quality of Adam Bolder into the squad. He is a great character and a leader.
"For whatever reason it didn't happen for him at Millwall. He wants to resurrect his career and we are going to give him the opportunity to do just that."