Wayne Rooney has raided former club Manchester United for the first time since his appointment of Derby manager with the arrival of centre back Teden Mengi.
Mengi, 18, will be at Pride Park on loan until the end of the season and has represented England at under-18 level.
Rooney was keen to bring in another defender in January following Mike te Wierik's unsuccessful spell at the club after moving from Eredivisie side Groningen in the summer before returning there permanently earlier this month.
Mengi has been training regularly with United's first team and made his debut for the Red Devils last August, coming on for Timothy Fosu-Mensah in the 84th minute as Ole Gunnar Solskjaer's side beat LASK in their round-of-32, second-leg Europa League clash.