A nightmarish painting by Francis Bacon has become the most expensive work of contemporary art sold at auction, only a day after sales records were broken by the late painter’s friend, Lucian Freud.

Triptych, 1976, described as the finest Bacon in private hands, sold to an anonymous bidder for $86.3 million (£44 million) at Sotheby’s in New York on Wednesday night. The previous record was set last May when Mark Rothko’s White Center (Yellow, Pink and Lavender on Rose) fetched $72.8 million.

On Tuesday a portrait by Freud, Benefits Supervisor Sleeping, sold for $33.6 million at Christie’s contemporary arts sale, becoming the most expensive work by a living artist.

Bacon and Freud were part of the London art scene during the Fifties and Sixties and close friends. Bacon, who was born in Ireland in 1909 to English parents, had no formal training as an artist but started to exhibit in the Thirties, achieving fame a decade later. He died of a heart attack in 1992.

Alex Branczik, of Sotheby’s, said of Triptych, 1976: “It showed Bacon working in a new way. It is a watershed painting which sees him moving beyond personal grief on to a more universal scale.”

Triptych, 1976 has featured in all the most important shows of Bacon’s work since it was first exhibited in Paris in 1977. Sotheby’s said that Wednesday’s auction, which made $362 million in total, was the best in its history.

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