Tulisa Contostavlos helped to supply cocaine to an undercover reporter who promised he could help the singer crack the movie business, a court has heard.
Reporter Mazher Mahmood, dubbed the "fake sheikh", posed as a wealthy film producer called Samir Khan and met the former N-Dubz star in Las Vegas and at the luxury Metropolitan hotel in London's Mayfair, jurors heard.
He promised the 26-year-old singer and former X Factor judge he could "get her a part in a big movie that was coming up" with Leonardo Di Caprio as her possible co-star, and she was keen to be "in his good books", prosecutor Tim Cray told London's Southwark Crown Court.
Contostavlos then allegedly boasted that she could "sort out" drugs for a boys' night out at a London strip club she was arranging for him.
She put Mr Mahmood in touch with her rapper friend Mike GLC who supplied the cocaine at a late-night rendezvous at London's five-star Dorchester Hotel, jurors heard.
The singer also allegedly bragged that she used to be part of a gang who sold crack cocaine and that her ex-boyfriend was a cocaine dealer.
But the illicit drug deal was taped and exposed in a front-page story in the Sun on Sunday newspaper last May, the court heard.
Mike GLC, whose real name is Michael Coombs, 36, pleaded guilty on Monday to supplying half an ounce (13.9g) of cocaine - which tests later showed was at 37% purity - for £860.
But Contostavlos continues to vehemently deny helping to broker the deal.
Opening the case, Mr Cray told jurors: "When the defendant had got involved in this drugs supply, she believed that Samir Khan was a film producer, a movie producer, a big shot.
"She thought he could get her a part in a big movie that was coming up and it seems that she was keen to be in his good books and be friendly with him."
Mr Cray said Mr Mahmood was staying in France, where he was posing as a high-flying producer.
He first arranged to meet Contostavlos in Las Vegas in March last year, and in May the pair met at the Metropolitan Hotel in Mayfair, during which they discussed whether Contostavlos was more suited to the film role than Kate Winslet or Keira Knightley.
Mr Cray told the court: "During the talk at the Metropolitan Hotel, the defendant said she used cannabis to help get to sleep and that she had connections to drug dealers.
"She then went on to say that one of her ex-boyfriends was a major cocaine dealer and that, back in her young days, she had been part of a gang that sold crack cocaine."
He said Mr Mahmood arranged to fly to London from France for a night out at a strip bar later that month, and received a call from Contostavlos at 10.30pm on May 21 to arrange it, when talk turned to whether cocaine would be available.
He said: "When the topic of drugs was raised, the defendant, Miss Contostavlos, said that she could definitely sort that out - that is, supplying cocaine to Samir Khan.
"She said she would need to make a few phone calls, but the drugs would be available from the next day, the Wednesday, when he got to London."
The singer texted him the next day stating: "Let me know when you land so I can sort you out."
Shortly afterwards she contacted Coombs to arrange the deal, it is alleged.
Mr Mahmood booked himself into the Belgravia suite of the five-star Dorchester Hotel in London's Mayfair, which boasts views over Hyde Park, a marble bathroom, a four-poster bed, and is "favoured by celebrated guests", according to the hotel's website.
And it was there at around 1am on May 23 last year that Coombs handed over the drugs, telling Mr Mahmood he had only gone to such trouble because he was good friends with Contostavlos, the jury of nine men and three women heard.
Mr Cray said: "In a sentence, therefore, the focus of what you have to look at and look at hard, we allege the defendant was instrumental in arranging the supply of cocaine carried out in the Dorchester early on the Thursday morning.
"Putting it plainly, she had said that she could arrange for cocaine for Samir Khan - 'sorting him out' - she put him in touch with one of her friends, Mr Coombs, who did the deal. Mr Coombs was expecting the call and stated in terms that he was prepared to put himself out on the defendant's behalf.
"Therefore, although the defendant had not negotiated the price or amount, the crown's case is she had done all she could to make a supply of cocaine happen and the charge reflects her involvement in the supply of the drug."
But Mr Cray said that rather than endear herself to a powerful film producer, Contostavlos had her face splashed across a national newspaper.
He said: "She was part of a sting by the Sun newspaper. She fell for it.
"It certainly made for a good newspaper story, because the defendant had been a member of a pop group, a judge on a TV talent show, and is generally well known in the world of entertainment."
Dressed in a black dress and black and white and patterned jacket, with her hair in a ponytail, Contostavlos looked straight ahead from the dock as the prosecutor delivered his opening speech.
Mr Cray warned the jury to keep their "feet firmly on the ground" when considering the case, and not be swayed by the glitz and glamour of "showbusiness, journalism and the world of celebrity".
He said: "Trips to Las Vegas, expensive hotel bars and restaurants in the West End of London are not the sort of life that most people routinely come across.
"But a moment's thought will make you realise the defendant deserves to be judged by the same fair standards that anyone coming before these courts is entitled to.
"Therefore, we suggest that you should put all the glitz and publicity to one side."
Mr Cray said Mr Mahmood had posed as a wealthy producer staying in Cannes in the south of France for the world-renowned film festival.
The undercover reporter had gained Contostavlos's trust, Mr Cray said, and in one phone call played to the court she spoke to him about breaking up with her boyfriend, a footballer, whom she described as an "arsehole".
Mr Mahmood met the singer in Las Vegas while she was in America trying to boost her acting career, and dined with her at Nobu, the popular celebrity hangout, in London, the court heard.
While at the Metropolitan Hotel with Mr Mahmood on May 10 last year, the singer spoke about being able to get "white sweets" - slang for cocaine - and "green sweets" for cannabis, it is alleged.
In a conversation on May 21 she spoke to Mr Mahmood again and promised him "white sweets" for a boys' night out at an east London strip club run by her ex-boyfriend, Adam Bailey, jurors heard.
The court was played the phone call in which the reporter said: "What about white sweets?", and Contostavlos replied: "Yes, definitely on the day.
"I can definitely sort it. I just need to make some more calls."
On May 22 she texted Mr Mahmood, writing: "Let me know wen u land so I can sort u out! Love Tulisa xxx."
Shortly afterwards she texted Coombs, saying: "Okey dokey, I have a number for u to call of my good friend that will sort u out, give me a ring in a bit."
The drug deal happened in the early hours of May 23.
Contostavlos was arrested last June and in a written statement said she had spoken to Mr Mahmood in an "exaggerated manner" and was "playing a role", the court heard.
"The impression given in the Sun newspaper is misleading," she told police.
"My words have been taken out of context.
"I'm not a drug dealer. I didn't initiate the supply of drugs to the Sun journalist."
Mr Mahmood entered the witness box and gave evidence from behind a screen to protect his identity.
Journalists and members of the public were told to leave the court briefly while the undercover reporter entered the room.
Mr Mahmood said he was playing the role of a film producer from India when he met Contostavlos with another undercover reporter in Las Vegas and at London's Metropolitan hotel last year.
"We claimed to be from India and we wanted to make an international film with a substantial budget and we wanted to befriend Tulisa Contostavlos," he said.
Mr Mahmood said Contostavlos brought up the topic of drugs during their meeting at the Metropolitan hotel on May 10.
"She brought it up with words to the effect that she would go home tonight and have a drink and she might have cannabis to go to sleep," he told the court.
They discussed drugs again later at the hotel bar when the singer said she was not a cocaine user but did smoke cannabis, Mr Mahmood said.
It was then that she spoke about being being able to get "white sweets" - a slang for cocaine - and "green sweets", meaning cannabis, he added.
Asked what he understood Contostavlos meant by "white sweets", Mr Mahmood said: "That she could supply me with cocaine, no problem."
A video was played to the court showing Coombs removing drugs from his sock or shoe after meeting Mr Mahmood at the Dorchester Hotel.
Contostavlos, of Friern Barnet, north London, denies helping an undercover reporter to obtain 0.5oz (13.9g) of the Class A drug for £860.
The trial was adjourned until tomorrow.