Manchester United manager Sir Alex Ferguson ruled out a January transfer window spree on Friday despite a mounting injury crisis at his club.Midfielder Darren Fletcher this week became the latest player to join United’s casualty list, which already includes captain Nemanja Vidic and striker Javier Hernandez.But despite calls for Ferguson to bolster his squad the United manager said on Friday he will only buy if the right player becomes available. Asked if he expected United to sign any new players next month: “Not neccessarily. I don’t know why people keep going on about it.“I won’t buy unless someone appears we have always been interested in appears, but there isn’t.“Darren’s obviously such a great professional, it is not easy to replace that, but we will think about it.”Ferguson’s “thinking about it” is a reference to his existing in-house options, rather than a plan to operate in the transfer market and the United manager is already weighing up his alternatives.