Manchester United manager Sir Alex Ferguson has admitted that he is not happy with his side's recent penalty record.

The Premier League leaders beat West Ham United 1-0 courtesy of a Wayne Rooney goal in their FA Cup third-round replay at Old Trafford on Wednesday to advance to the next stage of the competition.

However, United have now missed five penalties this season following Rooney's second-half spot kick gaffe, and Ferguson is disappointed with his side's troubles from 12 yards out.

"I don't think it's one of these things, I think we have to improve on that," said Ferguson.

"There was talk about the boy [Rickie] Lambert at Southampton who has scored 31 out of 31. That's what penalty kick taking is all about.

"There are several great examples over the years. [Matt] Le Tissier [got] 47 out of 48. There was a player (Johnny Hubbard) in Scotland [who] played for Rangers [who scored] 57 in a row. Your penalty kick is your opportunity to take an advantage - whether it's a foul or a handball - of scoring a goal."

United will now host Fulham in the fourth round of the FA Cup later this month.