gain on vs verge upon

gain on

verb
  • To encroach on. 

  • To obtain influence with. 

  • To win ground upon; to move faster than, as in a race or contest. 

  • To get the better of; to have the advantage of. 

verge upon

How often have the words gain on and verge upon occurred in a corpus of books? (source: Google Ngram Viewer )