"Icons of Modern Art" at the Louis Vuitton Foundation features the cream of the staggering collection of 250 paintings put together by Sergei Shchukin before the Bolshevik Revolution, which had never before been seen outside Russia.
The show includes 29 works by Picasso, 22 by Matisse, 12 by Gauguin and other top-notch Cezannes and Van Goghs that the super-rich textile merchant picked up on trips to Paris before World War I.
With 60,000 people a week flocking to the spectacular though relatively modest-sized private gallery designed by Frank Gehry, its hours are being extended to try to cope with the demand, with doors opening seven days a week until 11:00 pm (2200 GMT) in February.
In the final week of the extended run, which ends on March 5, the foundation in the west of the French capital will stay open till 1:00 am.
The gallery -- paid for by the French luxury goods tycoon Bernard Arnault -- will lay on a breakfast every morning for visitors in the final week when doors open at 7:00 am, it told AFP.
That could end up amounting to quite a mountain of croissants as the show's attendance is already outstripping the blockbuster "Magritte" exhibit at the Pompidou Centre in Paris, which is currently pulling in 6,000 people a day.
As well as the impressionist and post-impressionist masterpieces, the exhibition also includes 30 major pieces from the Russian avant-garde suprematist and constructivist movements, loaned by the Tretyakov State Gallery in Moscow and the Russian Museum in St Petersburg.
Shchukin, who fled Russia for France after the revolution, had a particularly close relationship with Henri Matisse, whom he brought to Moscow in 1911 to decorate his palatial home.
He also commissioned two of the artist's most important works, "The Dance" and "Music", which are the centrepieces of the Paris show, curated by the former head of the city's Picasso Museum, Anne Baldassari.
Lenin himself signed the decree to expropriate the works, before Stalin scattered the collection to museums in Moscow and St Petersburg, condemning some of the greatest masterpieces of 20th-century art as "bourgeois and cosmopolitan".
The exhibition is the fruit of years of negotiations between LVMH boss Arnault and the Russian authorities, with a partnership agreement signed last year between the foundation and the Hermitage Museum in St Petersburg and Moscow's Pushkin Museum.