Aleah Chapin's nude portrait of a family friend has been named the winner of this year's BP Portrait Award.
The 26-year-old American painter has won the prestigious first prize of £25,000 and a commission worth £4,000.
The portrait, called Auntie, will go on display at the National Portrait Gallery this Thursday, 21 June.
It will be joined by 54 other entries, including Spanish artist Ignacio Estudillo's portrait of his paternal grandfather, which came second.
This year's four finalists, whose work can be seen in this gallery, were selected from 2,187 entries, received from 74 different countries.
29-year-old Jamie Routley - who is from Newport, Wales but lives in London - was the winner of this year's BP Young Artist Award.
He submitted a triptych of portraits of Tony Lewis, who has a newspaper stand at Baron's Court Tube Station and works in a wine shop.
London-based artist Alan Coulson, whose work previously featured in the 2010 and 2011 exhibitions, was awarded third prize for his painting of friend and fellow artist Richie Culver.
Director of the National Portrait Gallery, Sandy Nairne, said: "Aleah Chapin's portrait is ambitious and beautifully painted, with superbly controlled colour and tone.
"She is a very deserving winner of the 2012 BP Award, which once again demonstrates the vitality of contemporary portrait painting around the world."
Brooklyn-based Chapin has just completed a Master of Fine Arts (MFA) in painting at the New York Academy of Art, and has won several awards including the Posey Foundation Scholarship.
Her painting is part of a series of nude portraits of women Aleah has known all of her life, named The Aunties Project.
"The fact that she has known me since birth is extremely important," said Chapin. "Her body is a map of her journey through life. In her, I see the personification of strength through an unguarded and accepting presence."
The exhibition at the National Portrait Gallery runs until 23 September as part of the London 2012 Festival.