Wiktionary
vb. To challenge someone.
Usage examples of "go up against".
Did not our parents go up against the Kolder blindly and with only the strength within them?
And there was no particular stigma attached to losing, so that the system revolved around the losers' eagerly awaiting the next contest, the next chance to match wits, the next opportunity to go up against the big guys.
They'd played the avenging lover angle to the hilt, turned her into some sort of tragic heroine as she prepared to go up against the fearsome duelist who'd killed the man she loved.
They just want to see what might happen if they go up against Germany.
It was good to remember that, especially when you were about to go up against a cruiser in a destroyer you'd never commanded before.
Thus, if you go up against the Foanna, you shall be well matched, kind to kind.
If we go up against them, then we are once more gathered into their net—.
Archie thought it was just a toughie who packed his own, wanting to go up against a would-be-robber who only brandished a sawed off pool cue and patted his jacket pocket like it concealed a piece.