Ranting Susan Boyle completely lost her cool with two four-letter outbursts in a day, The Sun can reveal.

She stunned Britain's Got Talent fans, contestants and their families before going into meltdown later in front of hundreds of hotel guests.

There were fears last night that the pressure was getting to the show favorite.

Cops intervened at 5 p.m. yesterday after Susan, 48, went berserk in the lobby of the Wembley Plaza Hotel in North London when two strangers set out to "wind her up."

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One of two cops stationed at the hotel went up and asked: "Is there a problem?"

Susan, dubbed SuBo, roared: "Of course there's a f***ing problem."

PHOTOS: Click here to see photos of Susan Boyle.

Tears flowing, she turned on her heel and marched out the exit followed by her family, production staff and the cops.

One officer told her: "You are in the public eye, you must learn to expect this sort of thing."

A pal of Susan's told the star: "You can't act like this."

TV producers ushered her back upstairs after police finished speaking to her.

RELATED: Click here to read the full report from The Sun.