Manchester United boss Sir Alex Ferguson has sensationally challenged the FA Cup lawmakers!

Ferguson discovered a 128-year-old law that means replays can be avoided - and immediately tried to invoke it for today's fourth-round clash against Spurs.

The barely-known rule states clubs that draw their first game after 90 minutes can play extra time straight away - and not wait for a replay.

Fergie dismissed claims he was meddling with history. He argued: "It is in the articles of the Association that both teams can apply to have the game decided first time.

"The criticism would be we are not adhering to the principles and spirit of the FA Cup.

"But why have the FA got it in there? It is their problem. We will investigate it."

The FA confirmed the rule exists but TV companies will take legal action if anyone tries to make it happen.

Fergie's bid to invoke the rule against Spurs failed because both clubs have to inform the FA within seven days of being drawn against each other.

A Setanta source said: "We agreed a contract which gives us full access to each round and replays.

"We were not made aware of any loophole involving replays. If our coverage was cut back we would mount a legal challenge."

An FA spokesman said: "This rule is aimed at the preliminary rounds to help teams with geographical distances."