Nelson Freire, a reclusive pianist whose fabled technique and sensitive, subtle musicianship made him a legend among pianophiles, died on Monday at his home in Rio de Janeiro. He was 77.

His manager, Jacques Thelen, confirmed the death. He said Mr. Freire had been suffering from trauma after a fall in 2019, which led to surgery on his upper right arm and left him unable to play.

Mr. Freire was one of the greatest pianists of the past half century, possessing a gift that, in its grace of touch and its ease of virtuosity, recalled playing from the great masters of the half-century before that.

“You will be hard pressed to find a recital of comparable warmth, affection and finesse,” the critic Bryce Morrison wrote of a Debussy album from Mr. Freire in 2009, in words that might also have spoken for his artistry as a whole. “Here, there is no need for spurious gestures and inflections; everything is given with a supreme naturalness and a perfectly accommodated virtuosity that declare Freire a master pianist throughout.”

That Mr. Freire was indeed a master pianist had never been in doubt. A child prodigy, he gave his first performance at 4 and was attracting attention at international competitions before his teens. His playing had a wisdom that critics rarely failed to describe as innate.

“There was hardly a single forced or teasing effect, not a sigh of sentimentality, not a line of hectoring rhetoric,” Richard Dyer of The Boston Globe wrote of a recital of Franck, Ravel, Chopin, Villa-Lobos and Liszt in 1977. Mr. Freire, the critic continued, possessed “one of the biggest natural talents for the keyboard that I have ever heard.”

Even so, his profile remained relatively limited. Comparisons to Arthur Rubinstein and Vladimir Horowitz abounded, but Mr. Freire was an uncommonly reticent artist, giving fewer concerts than many of his peers, recording only rarely early in his career and remaining indifferent to publicity.

“There is a big difference between music and the music business,” he was quoted as saying in a 1992 profile in The Baltimore Sun. “It’s a completely different language, and when I get too involved in talking it, I get a little bit sick. As for talking about myself, it actually bores me.”

For much of his career, such reticence reduced aficionados, as The Sun put it, to treat “pirate Freire tapes with the veneration an art historian might accord to a recently rediscovered Rembrandt.”

But that began to change in Mr. Freire’s last two decades, when a series of recordings brought him wider attention.

“Whether Mr. Freire is shy or merely introspective, it is impossible to say,” Allen Hughes of The New York Times wrote of the pianist’s New York recital debut in 1971. He noted that Mr. Freire had “projected little of his own personality to the audience.”

“He was there, he played splendidly and that was it.”

Nelson José Pinto Freire was born in Boa Esperança, in southeastern Brazil, on Oct. 18, 1944. His father was a pharmacist, and his mother was a teacher who bought a piano for Nelson’s sister, Nelma, one of four older siblings. Nelson began to play from memory what he had heard Nelma practice. After 12 lessons of his own, each of which involved a four-hour bus ride down dirt tracks, his first teacher said that he had nothing left to teach the boy.

The family moved to Rio de Janeiro to find a new mentor; his father gave up his career to work in a bank there. But Nelson, then 6, was an unruly child, unwilling to be taught. With his parents about to give up, they found Lucia Branco, who had trained under Arthur de Greef, a pupil of Franz Liszt’s. Branco placed the boy with her student Nise Obino. “My relationship with her was very strong,” Mr. Freire said of Ms. Obino in 1995, “the strongest in my life.”

His break came in 1957, when he entered Rio’s first international piano competition and emerged a finalist. Brazil’s president, Juscelino Kubitschek, offered him a scholarship to study wherever he wanted to. He chose Vienna, and moved there at 14 to work with Bruno Seidlhofer, joining a class that included Rudolf Buchbinder and Martha Argerich, both of whom would go on to major international careers.

Ms. Argerich and Mr. Freire became frequent duo partners (and lifelong friends), both in concert and on record, her impulsive, electrifying style blending well with his tonal palette and impeccable timing.

“I didn’t do much work,” Mr. Freire nonetheless recalled of his two years in Vienna. He initially spoke no German and remained, after all, a teenager far from home.

Little success followed his return to Brazil, until he won first prize at the Vianna da Motta International Music Competition in Lisbon and the Dinu Lipatti Medal, presented in London, in 1964, accelerating his career in Europe.

Mr. Freire began recording for Columbia in the late 1960s, taping solo works by Schumann, Brahms and Chopin, as well as a double album of concertos by Tchaikovsky, Liszt, Grieg and Schumann, with Rudolf Kempe conducting the Munich Philharmonic. That album, Time magazine reported in 1970, “caught the critics by surprise and sent them scurrying for superlatives.”

Mr. Freire would scarcely return to the recording studio until 2001, after which he embarked on a golden period with Decca that produced nuanced, masterly releases of everything from Bach to Villa-Lobos, one of several Brazilian composers whom he played with pride.

Perhaps most valuable were standard-setting discs of the Chopin études, sonatas and nocturnes, as well as Brahms concertos with Riccardo Chailly and the Leipzig Gewandhaus Orchestra.

“This is the Brahms piano concerto set we’ve been waiting for,” the critic Jed Distler wrote in Gramophone in 2006, praising it for fusing “immediacy and insight, power and lyricism, and incandescent virtuosity that leaves few details unturned, yet always with the big picture in clear sight.”

Mr. Freire is survived by a brother, Nirval. His parents were killed in 1967 when a bus they were using to travel to hear Mr. Freire perform in Belo Horizonte, in their home state of Minas Gerais, plunged into a ravine.

Whatever repertoire Mr. Freire turned to, he had a depth of tonal variety, a poetry of phrasing and a natural, almost joyous refinement.

In “Nelson Freire,” a 2003 documentary film, he is shown watching a video of a joyous Errol Garner playing jazz piano. “I’ve never seen anyone play with such pleasure,” he said.

“That’s how I found the piano,” Mr. Freire continued. “The piano was the moment, when I was little, when I felt pleasure. I’m not happy after a concert if I haven’t felt that kind of pleasure for at least a moment. Classical pianists used to have this joy. Rubinstein had it. Horowitz had it, too. Guiomar Novaes had it, and Martha Argerich has it.”

What about you, the interviewer asked?

Mr. Freire lit a cigarette, looked up shyly, and smiled.