Yo-Yo Ma joined Riccardo Muti and several youth music ensembles for a  performance in Chicago on Sunday that marked the end of the 11-day Chicago Youth in Music Festival.

Ma, a creative consultant to the Chicago Symphony Orchestra (CSO) and one of the figures helping to drive the orchestra's community engagement activities, performed solo and in the cello section of a group of 12 string players drawn from the CSO, Civic Orchestra of Chicago and Chicago Youth Symphony.

The cellist had earlier sneaked into an open rehearsal conducted by CSO music director Muti, taking a seat in an orchestra comprising Chicago high school students and visiting members of the Carlos Chávez Youth Orchestra of Mexico. According to the Chicago Tribune, a few of the cellists couldn't help conceal their surprise as Ma joined them, but Muti never even noticed him.