Update: We have confirmation of the Rajkovic and Matic moves from the Chelsea site.
Chelsea defender Slobodan Rajkovic and midfielder Nemanja Matic have been shipped out on loan to Eredivisie side Vitesse, with recently-acquired goalkeeper Matej Delac seemingly set to follow them upon completion of a physical. Note: The link is to Vitesse's official site, and therefore is in Dutch, so this is a (bad) paraphrasing.
We've talked about the alarming lack of defensive depth following the sale of Ricardo Carvalho and the permanent loss of Sam Hutchinson, and Rajkovic going away doesn't help matters any. Fortunately, Jeffrey Bruma will be back in training soon, but don't rule out the Blues spending on a defender before the deadline.