Sir Alex Ferguson claims Manchester United have a strong case after defending Manchester United's ongoing attempts to challenge Rio Ferdinand's ban for violent conduct.

Ferdinand risks missing the Carling Cup Final against Aston Villa on February 28 should the Football Association decide that a second appeal relating to the England defender's clash with Hull City's Craig Fagan during a Premier League game in December is again 'frivolous'.

The 31-year-old centre-half saw his automatic three-match suspension for being charged with violent conduct increased to four games last month.

United and Ferdinand will now appeal the additional ban in a controversial move which has led to criticism.

The Old Trafford club will cite the example of Liverpool's Javier Mascherano when he appeared to get away with a similar incident involving Leeds United striker Jermaine Beckford during a Carling Cup game back in September.

"The concern is the word frivolous," explained Ferguson.

"The two most experienced referees in the Premier League are Alan Wiley and Steve Bennett.

"They are under the same controls and the same directions. One says yes (Bennett) in the case of Rio, and one says no (Wiley) in the case of Javier Mascherano against Leeds United, when he punched the player in the back of the head.

"When you see that example, we don't think our appeal was frivolous."Subscribe to Football FanCast News Headlines by Email