Niklas Sivelöv composed his Sonata for Tuba and Piano, op5 between 1991 and 1992 for Oystein Baadsvik. It has three movements and is a technically demanding work. The sonata unites two traditions, as it combines the musikantisch Spiel tradition with more modernistic style in which the exploration of the instrument's tonal resources is an important element.

The first movement presents two thematic ideas, the first prosaic, recitatively designed with wide intervals, and the second more rhythmic and melodic with somewhat narrower intervals. Roughly speaking, the whole movement can be said to unfold within the field of tension between these two ideas and closes with a cadenza played by the tuba, which leads into the second movement. This variations movement has the character of an intermezzo.

The final movement has a strong rhythmic orientation and is approaching the ecstatically ritual in its forcefulness when it finally picks up reminiscences from the works opening.

The sonata is part of the Jeju international competition repertoire.