HONG KONG - Auction house Christie's unveiled on Monday what it called "the highest-estimated Asian artwork" to ever go under the hammer, a Xu Beihong painting called "Slave and Lion," which it expects to fetch between $45 million and $58 million.

The 1924-dated painting by Xu, who is regarded as one of the most important figures of Chinese realism, will go on public preview in Beijing and Shanghai this month before being auctioned in Hong Kong on May 24.

The painting was sold in the global financial hub in 2006 at Christie's for HK$53.9 million ($6.9 million), a record at the time for a Chinese oil painting.

"The market at the very top is very strong; (there is) a lot of demand, extremely driven by rarity, which is exactly what this work is about," Christie's Asia Pacific President Francis Belin said.

The story behind the painting is rooted in Roman mythology, according to Christie's presentation.

A runaway slave was captured and, as punishment, thrown into the Colosseum with a lion. But the animal did not attack the slave, who had earlier removed a thorn stuck in the lion's paw. The slave and the lion were eventually set free. ($1 = 7.7706 Hong Kong dollars)

(Reporting by Joyce Zhou, Writing by Marius Zaharia. Editing by Gerry Doyle) ((marius.zaharia@thomsonreuters.com; +852 2843 6358;))