Something or someone difficult to rival or beat: Dr Nick's going to be a hard act to follow
[1975+; from the notion of a performer coming next on a variety bill]
A challenging or daunting prelude: her portrayal of Cat-woman was a tough act for Michelle Pfeiffer to follow
[1980s+; fr the vaudeville ambiance where one performer succeeded another; one truism was ''Never follow a dog act'']