The 20-year-old signed a six-year contract at Stamford Bridge in August, and has impressed for the Blues, scoring four times in eight starts for Chelsea's Under-21 side. The Italian, who joined Chelsea from Inter Milan, has already begun training with his new club, who sit 16th in the Championship. Manager Paul Ince told the club website: "Our midfield resources have been stretched all season and Casadei will bring us another option in the middle of the park. "He is comfortable on the ball, powerful in possession and he looks like an intelligent player with the vision to read the game well.
Manchester City are not expected to sign a replacement for Bayern Munich-bound Joao Cancelo.
Wrexham will face Tottenham Hotspur in the FA Cup fifth round if they can overcome Sheffield United in their replay. John Egan scored a late equaliser as the Blades denied Wrexham a direct route into the next round on Sunday, and the pair will have to face each other again at Bramall Lane. Manchester City will travel to Bristol City for their fifth-round clash, with the sides having not played each other since the Carabao Cup semi-finals in 2018.