text: In February 1914 , at age eleven , he made his concert debut , playing Joseph Haydn 's Cello Concerto in D major with the Vienna Philharmonic conducted by Felix Weingartner .
simplified: In February 1914 , aged twelve , he played in his first concert , performing Joseph Haydn 's Cello Concerto in D with the Vienna Philharmonic conducted by Felix Weingartner .