give (one) a run for (one's) money

To challenge one's ability, fortitude, or patience. Don't underestimate our opponents today—I think they'll give us a run for our money. Having an infant and a toddler sure is giving me a run for my money. Sure, Sheila still became valedictorian, but Tim really gave her a run for her money!

run for one's money, (give) a

A close contest or strong challenge; to give a good return for one’s expense. This term may come from the racetrack, where it is used to describe deriving pleasurable excitement from a horse race even if one does not win all one’s bets. The term appeared in a dictionary of slang in 1874 and has been used ever since. “They have had what is called in some circles a good run for their money,” reported the Pall Mall Gazette in 1889.