Pablo Picasso's Femme assise pres d'une fenetre is expected to reach up to £35 million when it is sold at auction next week.

The painting, from 1932, will be sold by Sotheby's on 5 February and it is estimated to reach between £25 million and £35 million.

It is being sold by a private seller and is a portrait of the artist's 'golden muse' Marie-Therese Walter.

Marie-Thérèse was Picasso's young lover. He first met her when she was 17 and their love affair became a compelling tale of the 20<sup>th century.

His pictures of her were at first veiled as he was married to Olga Khoklova. However, they were presented for the first time in 1932 in Paris alongside other Cubist and Surrealist works, and his secret was revealed.

The repeated face of Marie-Thérèse among his collection made Khoklova aware her husband had another woman in his life.

Khoklova and Picasso separated shortly after she found out about Marie-Thérèse but were never divorced.

Speaking years after they first met, she once said: "'I was an innocent girl. I knew nothing - either of life or of Picasso ... I had gone to do some shopping at the Galeries Lafayette, and Picasso saw me leaving the Metro.

Picasso's most celebrated period

"He simply took me by the arm and said, 'I am Picasso! You and I are going to do great things together'."

Marie-Thérèse had a child with Picasso and she took her own life four years after he died in 1973.

Helena Newman, chairman of Sotheby's Impressionist and Modern Art Department Europe, said: "We are delighted to present a sale this February that includes such important and hugely appealing works that span right across the Impressionist & Modern Art field, spearheaded by Picasso's 1932 work Femme assise près d'une fenêtre.

"In recent years in particular we have witnessed the remarkable allure of Picasso's portraits of Marie-Thérèse to collectors, with La Lecture selling for £25 million - double its pre-sale estimate - in Sotheby's February 2011 sale, and Nature morte aux tulipes selling in Sotheby's November 2012 sale for $41.5 million (£26.4 million).

"This particular portrait is a striking and notably modern-looking work from one of the artist's most celebrated periods."

The most expensive Picasso ever to sell at auction was the 1905 painting Garcon a la Pipe, which sold in a Sotheby's auction in 2004 for £58 million.