The auction record for post-war art has been smashed twice in one night.
Mark Rothko's painting was sold by philanthropist David Rockefeller
Francis Bacon's portrait Study from Innocent X fetched $52.6m (£26.5m) at Sotheby's in New York - almost double the previous high for a Bacon work.
That was followed by a price of $72.8m (£36.7m) for US abstract artist Mark Rothko's 1950 work White Center (Yellow, Pink and Lavender on Rose).
They were far ahead of the last modern art auction record, the $27m (£13.6m) for Willem de Kooning's Untitled XXV.
New auction records were set for 15 artists in total, also including Jean-Michel Basquiat, whose untitled work from 1981 fetched $14.6m (£7.4m), almost three times his previous best.
The Rothko was sold by philanthropist David Rockefeller, who attended the auction.
The work had hung in his office since he bought it for less than $10,000 on the advice of Dorothy Miller, the first chief curator at New York's Museum of Modern Art, in 1960.
The auction house hailed the painting's "commanding scale, sumptuousness and sheer intensity" as a mark of "a modern master in the first full flush of his mature creativity".
Francis Bacon created Study from Innocent X in 1960
The Bacon work came from a series based on 17th Century Spanish artist Diego Velazquez's Portrait of Pope Innocent X.
It had been in the same private collection for more than 30 years and had never been sold at auction before.
Other high prices included $10.7m (£5.4m) for Robert Rauschenberg's Photograph and $5.9m (£3m) for Tom Wesselmann's Smoker #17.
Andy Warhol's Large Campbell's Soup Can sold for $5.5m (£2.8m), while Roy Lichtenstein's Still Life with Green Vase made $4.3m (£2.2m).
New records were also set for artists including Richard Prince, Hans Hofmann, Morris Louis and Dan Flavin.
"We're obviously thrilled with the results," Sotheby's auctioneer Tobias Meyer said.
Andy Warhol's Lemon Marilyn goes under the hammer on Wednesday
The sale included "lots of international bidding" and "showed how aggressive and strong the contemporary art market is", he said.
Last November, the New York Times reported that a 1948 work by Jackson Pollock became the most expensive painting ever sold when it changed hands for about $140m (£73m) in a private sale.
The big bids are expected to continue on Wednesday, when Christie's holds its contemporary art sale in New York.
The main attractions are expected to be Warhol's Green Car Crash, which has an estimate of $25m-$35m (£13m-£18m), and his Lemon Marilyn, which is valued at more than $15m (£8m).
The record for a work by the late pop artist currently stands at $17.4m (£8.8m), paid for a 1972 portrait of Chairman Mao last November.