An original painting by Tintin creator Herge could set a new record for a comic book sale when it goes to auction in Paris on Thursday.
The online sale is widely expected to confirm the huge appetite for memorabilia of Tintin, whose adventures have entertained people of all ages since the 1930s.
The previous world record for comic book art was set in 2014, when a double-page ink drawing that served as the inside cover for Tintin volumes published from 1937 to 1958 sold for 2.65 million euros ($3.6 million at the time).
The small painting being offered on Thursday, measuring 34 cm square (13 inches), features Tintin and his dog Snowy emerging from a porcelain jar in front of a menacing depiction of a Chinese dragon.
It was intended for the cover of "The Blue Lotus" from 1936 but was judged too expensive to reproduce by the publisher, which ultimately used a simplified version of the same scene, auction house Artcurial says.
The volume, the fifth in the Tintin series, is considered a milestone in Herge's development of the character with its more dynamic and realistic storylines alongside his meticulous artwork.
The auction house estimates it will sell for 2.2 to 2.8 million euros, despite clear fold marks. The sale had originally been set for November.
In 2016, an original drawing from Tintin's "Explorers on the Moon" book sold for 1.55 million euros, a record for a single comic book page.
Herge, a Belgian whose real name was George Remi, sold some 230 million Tintin albums by the time of his death in 1983.
According to the owners -- heirs of the Tintin publisher Louis Casterman -- the drawing on sale Thursday was given as a present by Herge to Casterman's son, who kept it folded up in a drawer.
Other experts have cast doubt on this, saying the drawing might have been folded by Herge himself when he sent it by post to his publishers.
"The theory that it was a gift to a child is outlandish," Benoit Peeters, an Herge expert who wrote a biography of the author, told French daily Le Monde in September.
"When Herge gave away sketches or drawings he always dedicated them, let alone for the son of his editor," Peeters said.
"What's most likely is that Herge never asked for it back, so it was given to Casterman's son."
Nick Rodwell, the British husband of Herge's second wife and rights holder Fanny Vlamynck, has said the work rightfully belongs in the Herge museum in Belgium.
For Philippe Goddin, a former secretary general of the Herge Foundation (now called Studios Herge), Casterman's claim the painting was a gift is "highly suspect."
"But the Castermans have done nothing wrong by putting the picture on sale. They believed the legend their father passed down," he told AFP.
© Agence France-Presse