US President Donald Trump has long claimed to have an original Renoir painting.
However, art experts from Art Institute of Chicago have insisted he is wrong, because the actual work is in their gallery.
Trump's biographer Tim O'Brien told Vanity Fair he challenged the real estate tycoon several years ago after spotting the copy in the latter's private jet.
Pointing out the picture hanging in the jet, Trump boasted: "You know, that's an original Renoir."
O'Brien grew up in Chicago and knew the original well, which has hung in the Chicago museum since 1933.
However, O'Brien replied: "Donald, it's not. I grew up in Chicago, that Renoir is called Two Sisters on the Terrace, and it's hanging on a wall at the Art Institute of Chicago."
The following day, Trump appeared to have forgotten the previous day's conversation, and declared: "You know, that's an original Renoir."
After Trump sold the private jet, the painting ended up in Trump Tower in New York and featured in the background of a Fox News interview with his wife Melania last year.
O'Brien said: "I'm sure he's still telling people who come into the apartment, 'It's an original, it's an original.'
"He believes his own lies in a way that lasts for decades. He'll tell the same stories time and time again, regardless of whether or not facts are right in front of his face."
Art Institute spokeswoman Amanda Hicks has come forward to support O'Brien, stipulating the institute is "satisfied that our version is real".
10 incredible auctions
10 incredible auctions
The most expensive watch ever sold at auction fetched just under $24 million in November 2014. The gold pocket watch was made by Patek Philippe, and is the most complex ever made without the use of computer technology.
The Henry Graves Supercomplication was commissioned in 1925, and took eight years to make.
The world's most expensive stamp sold at auction in 2014 for over $9 million.
The British Guiana One-Cent Magenta is as rare as a stamp can get. British Guiana was one of the first countries in the New World to start issuing stamps, but in 1856, they ran out, and asked the local newspaper printer to produce extras.
There were two denominations: the four-cent, which is very rare, and the one-cent - of which only one has ever been discovered.
In May 2015, an anonymous London businesswoman snapped up the licence plate KR15 HNA for £233,000, making it the most expensive standard number plate ever to be sold in the UK.
Queen Victoria's bloomers sold at auction for £6,200, along with a pair of her silk stockings.
They have a 52-inch waist, and belonged to the monarch in the 1890s - "towards the end of her life when she had eaten a lot more than most people could afford to," said auctioneer Michael Hogben. In today's sizing, they'd be a size 26.
In 2014, a three-year-old slice of cake sold at auction for $7,500 (£4,800). The reason the stale cake was in such demand was that it was from the marriage of Prince William to Kate Middleton in 2011.
The buyer said he intended to give it away as part of promoting his Silicon Valley start-up.
A British coin sold at auction for a record-breaking £430,000 in 2014. After fees, the buyer paid £516,000 - making it the most expensive modern British coin ever to be sold.
The coin is only one of two in existence. It was a 'proof' for a gold sovereign which was meant to be produced to commemorate the coronation of Edward VIII in 1937. However, Edward abdicated in 1936, so the coronation never happened and the coins were never made