Rotterdam, Netherlands ? Musicologists puzzled over a lost Ludwig van Beethoven concerto for decades, ever since the 1960s discovery of the sketch of a single movement among the composer’s papers.

Now, two Dutch Beethoven enthusiasts have pieced together the musical clues, put them into 18th-century orchestral context and reconstructed the second movement of the only oboe concerto Beethoven ever wrote.

The slow, melodic Largo movement of the Oboe Concerto in F Major was performed Saturday night in Rotterdam and billed as a “world premiere” — even though the full concerto was performed at least once before, 210 years ago.

“Premieres happen all the time. But a Beethoven piece that’s never been heard?” said Conrad van Alphen, conductor of the Rotterdam Chamber Orchestra. “To have a Beethoven premiere is really special.”

The eight-minute piece was slipped into an evening of concert standards by Mozart and C.P.E. Bach without fanfare, barring a bold-print note on the program announcing the “premiere.”

The audience gave the movement warm applause but saved their standing ovations for more familiar pieces on the program.

True, the recovered concerto is from an early work and gives little foretaste of the majestic symphonies he wrote while going deaf. The movement reveals a cautious Beethoven — then a 22-year-old student — still influenced by Mozart and his teacher Franz Josef Haydn.

Nonetheless, recovering the movement is significant — mostly because of all the genres of music in Beethoven’s prolific career, the oboe concerto was among the few he hardly touched.

Beethoven wrote the concerto in 1792 as an exercise under Haydn and revised the second movement the following year. It would be several more years before he published his Opus No. 1, announcing himself as a composer.

The only known copy of the oboe concerto vanished from a Vienna publishing house in the 1840s. Its existence was confirmed in 1935, when researchers found an exchange of letters between Haydn and Beethoven’s sponsor, in which the Austrian composer seeks a further stipend for his young German pupil.

The sponsor’s letter confirmed the oboe concerto had been performed in Bonn, Germany.

Next, a Beethoven scholar found the opening notes of all three movements in a Bonn library and published them in 1964. Another scholar examined bundles of Beethoven’s sketches, or drafts, in the British Library and, working with the clues found in Bonn, could identify the oboe concerto’s second movement.

Since then, experts have tried to rebuild the movement, but Jos van der Zanden and Cees Nieuwenhuizen are believed to be the first to do so with full orchestration.

Van der Zanden, a musicologist with Dutch radio and a frequent contributor to the Beethoven Journal published in San Jose, Calif., worked for more than a year with composer Nieuwenhuizen to reconstruct a “sober 18th-century accompaniment.”

The two “had the skeleton, from the first to the last note,” but were uncertain which passages were intended for the oboe soloist and which for the orchestra. Scoring the orchestration, they inferred harmonies from the way similar concertos were composed at the time, Van der Zanden said.

The sketches also had clues for the full score — a few marks and symbols above the staves indicating chords, cadences or links to other passages.