Wiktionary
out of one's league
a. 1 (context idiomatic English) In a situation in which one is mismatched with one or more others whose accomplishments, preparedness, or other characteristics are on a significantly higher or lower level than one's own. 2 (context idiomatic English) out of one's depth; in a situation which one is poorly prepared to handle. 3 (context idiomatic English) Too good or too expensive for one.