"Just before the shoot-out I was looking at an iPod and on it were Tottenham's penalties, including one from O'Hara," said Foster.
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"They just told me to stand up, be strong and it will probably go that way. It is a new innovation."
Foster also made excellent saves in normal time from Aaron Lennon and Darren Bent, with Ferguson adamant that the 25-year-old will succeed Edwin van der Sar at Manchester United and David James with England.
"The future is his," said Ferguson. "The present belongs to Van der Sar. Given that experience in a final, that strengthens his [Foster's] belief. I think he'll be England's goalkeeper for the next number of years"
Ferguson, though, was highly critical of referee Chris Foy's decision to book Cristiano Ronaldo for diving following a challenge from Ledley King. "It's ridiculous – it's a penalty kick," said Ferguson. "He [Foy] couldn't wait to book him."
United have now already won two trophies amid excited talk of an unprecedented 'quintuple' this season. "It would be great to think we could do it, but my experience says we could go to Fulham and a deflected shot off someone's backside and we're out of the FA Cup," said Ferguson.
David Bentley also missed a penalty for Tottenham, shooting wide after the match had finished goalless in normal time. "It was a poor penalty for a player who can strike a ball as well as he can," said Tottenham manager Harry Redknapp.