in contention vs problematical

in contention

prep
  • Used other than figuratively or idiomatically: see in, contention. 

  • Contending for a title or championship. 

problematical

adj
  • dubious or ambiguous 

  • doubtful or disputed 

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