In 1941, Clarke was hired by Hill, who had become the manager of Minton's Playhouse in Harlem, to handle the music at the club. Clarke was given free rein over whom he could hire and which style of music he could play. The house band consisted of trumpeter Joe Guy, pianist Thelonious Monk, bassist Nick Fenton, and Clarke on drums. Regulars at the club included Gillespie and guitarist Charlie Christian, and bandleaders such as Count Basie, Duke Ellington, and Benny Goodman listened to or participated in the sessions. In his entry on Clarke in "American National Biography", Barry Kernfeld wrote: "The sessions became famous for demonstrations of virtuosity—unexpected harmonies, fast tempos, unusual keys—that discouraged those whose style did not fit in well. These experimental sounds were crucial to the development of bebop." It was in this setting that Clarke and Monk co-wrote the jazz standard "Epistrophy", originally known as "Fly Right". He then led his own band at Kelly's Stables in New York, the Kansas City Six, featuring tenor saxophonist Ike Quebec, where the two are said to have come up with the riff tune "Mop Mop", played in a septet with saxophonist Benny Carter, and performed with Red Allen's band in Boston and Chicago.