Ronaldo is felled by Woodgate in the FA Cup replay

Boro backroom staff reacted furiously after Ronaldo won and scored the late penalty in United's 1-0 win in the quarter-final replay at Old Trafford.

Ferguson said: "I don't know what they are going on about, it was a penalty.

"If it had been any other player they would not have bothered but they have a guilt complex about him."

Interview: Man Utd's Cristiano Ronaldo

Ronaldo tumbled under a challenge from Jonathan Woodgate and scored from the spot to clinch a semi-final encounter against Watford.

Middlesbrough were also furious earlier this season after Ronaldo won a penalty in a Premiership clash at the Riverside.

But Ferguson added: "It is a shame. They are putting a stigma against the boy that he doesn't deserve.

"We have had some great players at this club in my 20 years here and Cristiano is up there with the best of them. He is phenomenal."

Ferguson's assistant Carlos Queiroz had to be pulled away from the Middlesbrough management and coaching staff at the final whistle.

But Southgate refused to condemn his team or staff, saying: "The galling thing for me is that we have played them three times this season and conceded three dodgy penalties.

"In the heat of the moment, everybody is entitled to a reaction.

"It is the 75th minute of an FA Cup quarter-final. People are going to react in a way you wouldn't normally."

And after James Morrison's wild, late lunge on Ronaldo, which earned the youngster a red card, Southgate added: "We certainly lost our discipline in the last five minutes. James Morrison is a young kid and he has a lot to learn.

"In that situation, we would all love to do that but you have got to be mature enough to make the right kind of tackle."

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After scoring the winner, Ronaldo was asked why he thought controversial decisions seemed to follow him.

He said: "Maybe some people don't like me. Maybe I'm too good."

"For me, it is a penalty. Why when I am involved is it always polemic?"

Ronaldo insists he did not go down too easily under Woodgate's challenge.

He added: "Of course I felt contact, that is why I slipped. He touched.