MANCHESTER - David Moyes, the increasingly beleaguered Manchester United manager, admits he urgently needs to buy new players in the January transfer window but confesses that it may not be possible to do so.The Scotsman was talking in the wake of another major disappointment for his club as United, record 11-times winners of the FA Cup, were knocked out at home in the third round by Swansea.The 2-1 defeat marked United’s fourth home loss in their last six games at Old Trafford and just the second time in 29 years that the club has been knocked out in the third round of the competition.Moyes only brought in Marouane Fellaini, from his former club Everton, after taking over at Old Trafford in the summer and with every growing setback, pressure is mounting on him to improve a squad that is looking well beyond par and which was without seven injured first team players on Sunday."I said I would try but probably would be doubtful in January because of the window but I think I have been saying it fairly consistently,” said Moyes of his efforts to sign new talent this month."There is an urgency that we would like to bring people in but are those players available in January?”The most glaring absentees from the United side were forwards Wayne Rooney and Robin van Persie while the late dismissal of young defender Fabio certainly did not aid United’s cause as they fell to a last minute goal from Wilfried Bony.However, Moyes refused to use the absence of key personnel as an excuse for a defeat which also featured a goal for Wayne Routledge and a quick United reply from Javier Hernandez.United and Moyes at least have the opportunity to respond quickly, with a League Cup semifinal first leg awaiting in Sunderland on Tuesday although Rooney and van Persie remain major doubts for the tie.