Oscar Peterson and Clark Terry go back a long way and have recorded together in a variety of situations, formal and informal. When Peterson planned his series of duo encounters with the greatest trumpeters in jazz it was a foregone conclusion that one of them would be with Terry. In terms of technique, it was an even match, as proved in a furious version of “Shaw ’Nuff” and in the appropriately named “Chops.” But the album also includes ballads that bring out the lyricism in both men, and a slow blues that makes plain the essential nature of their musical characters.