play up vs undervalue

play up

verb
  • To make or attempt to make something appear more important, likely, or obvious; to showcase or highlight. 

  • To play more vigorously. 

  • To be unfaithful to a lover; to cheat; used with on. 

  • To misbehave. 

undervalue

noun
  • An undervaluation; a price or rate below the actual worth. 

verb
  • To underestimate, or assign too low a value to. 

  • To have too little regard for. 

How often have the words play up and undervalue occurred in a corpus of books? (source: Google Ngram Viewer )