eye to the main chance, have an
Look out for one's own best interest. For example, Tom is watching the company's progress very closely; he always has an eye to the main chance. [c. 1600]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.