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one up (on someone)
Leading or ahead (of someone); in an advantageous position (over someone). He's just mad because Sarah is one up on him after their yearly performance reviews. Jake and I have an ongoing contest to see who's better at this game. He's one up at the moment, but I'm trying to improve.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
*one up (on someone)
ahead of someone; having an advantage over someone. (*Typically: be ~; get ~.) Tom is one up on Sally because he got a job and she didn't. Yes, it sounds like Tom is one up.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
Having an advantage or lead over someone, as in Sara is one up on Jane because she passed algebra in summer school. This expression comes from sports, where it means to be one point ahead of one's opponents. It was transferred to more general use about 1920.
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.