Millwall have completed the loan signing of Derby defender Alex Pearce.
The 30-year-old, who has featured only once so far this season, has joined the Lions for the remainder of the campaign.
Pearce is out of contract in the summer and will be free to join Millwall on a permanent basis if he impresses at The Den.
He will compete with fellow centre-backs Jake Cooper, Shaun Hutchinson and Murray Wallace for a starting place.
"I'm really pleased to be here," Pearce told the club's website.
"As soon as I heard about the interest from Millwall, I was excited about coming here and hopefully I can help the team climb up the league.
"The manager's enthusiasm was key. I met with him, we had a good chat, and we spent a good amount of time together.
"He was really positive - he told me about how he likes his teams to play, and I was really enthused by it all. Everything went really positively.
"I'll always give 110 per cent every time I'm asked to play."
One other player who could be leaving Derby in January is midfielder George Thorne, who has been given permission to speak to Sky Bet League One club Luton over a possible loan deal.
Meanwhile, Millwall manager Neil Harris has allowed Byron Webster to leave for Scunthorpe on a free transfer.
The 31-year-old made 137 appearances for Millwall during his four-and-a-half-year spell with the club and was part of the team that won promotion to the Sky Bet Championship in 2017.
Millwall face Hull in the FA Cup third round on Sunday before returning to league action against Blackburn on January 12, live on Sky Sports Football HD from 5.15pm.