After their surprise performance, girl group the Sugababes soon got to grips with life in the BB house.
The housemates gave the singing trio a guided tour of their pad, with Jeremy joking that "maybe we can then go to the hot tub or something".
Once they had seen the place first hand, the Sugababes settled down with the housemates in the seating area for a chat and a sip of champagne.
"I've heard you’ve got a lovely voice," said Heidi to a bashful Nathan, prompting calls for the R'n'B singer to perform for the chart-toppers.
Nathan was initially reluctant to sing, though after much encouragement was eventually coerced into it.
Stalling for time, he said: "I'm not going on stage, we'll just do it here," drinking some water for his suddenly dry throat.
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An impatient Anthony cried: "Come on, sing already," forcing Nathan to launch into one of his songs.
The housemates and celebrities applauded once the song was finished with calls for another.
Nathan turned down the pleas for a second song, overwhelmed that he had sung live to the Sugababes. "Wow - this is crazy," he remarked.
