come up against someone—(also: go up against someone) challenge a competitor in a contest, election, etc:
- Although he rode very well, he came up against an opponent who tactically rode even better.
run up against someone—
1. meet a person, especially by accident:
- You can’t go anywhere in London without running up against him.
2. = come up against someone:
- I also had the sense that Tony would be a formidable adversary if you ran up against him in court.