It was a performance that might help bridge a gap in our understanding of the development of one of the world's great composers.

Two short works that seem to be by Wolfgang Amadeus Mozart wereposthumously premiered on Mozart's own piano. One piece was theharpsichord part for the Concerto in G (molto allegro) and the other was the Prelude in G major.

The pieces formed part of Nannerl's Music Book, a collection of musiccompiled by Mozart's father, Leopold Mozart.

Dr Ulrich Leisinger of the International Mozarteum Foundation believes that the two pieces were composed by Mozart and then transcribed by his father.

According to the expert, the Concerto in particular is significant because it could be the 'missing link' between the simple works Mozart created as a child prodigy and the masterpieces that he produced when he was an adult.

Researchers at the Mozarteum believe the Concerto was composed by the young virtuoso in 1763 or 1764, when he was around eight years old. That is ten years earlier than the piano concerto that is currentlyrecognised as being Mozart's first. But the piece is much moretechnically demanding than the miniatures he wrote as a young child.

"This was a young composer running riot to show what he was capable of," Dr Leisinger said.

Yet Mozart's adolescent desire to show off his technical mastery did not, on this occasion, create a masterpiece.

"The piece does contain real technical mistakes and clumsy moments that an old hand like Leopold Mozart would never have made," Dr Leisinger added.

The researchers describe the newly-found Prelude in G major as slightly more "refined" than the Concerto.

When he died aged 35, Mozart left behind more than 600 works, including operas, chamber works and piano concertos. Who knows how many more pieces by the master lie waiting to be discovered?