Mauricio Pochettino is now beginning to think that Chelsea may need to sign a new defender this month. That is according to transfer speculation this week. The Blues are set to lose a left-back option from their squad with Ian Maatsen, 21, tipped to be leaving on loan. Journalist Fabrizio Romano claimed earlier today on X that Maatsen’s signed a two-year contract extension with Chelsea ahead of a switch this week to Borussia Dortmund on loan for the rest of the season. There’s now a suggestion that Maatsen’s imminent exit could tempt Chelsea head coach Mauricio Pochettino into signing a new le…