Idiom: "A run for the money" or "A run for his money"
It's used in the sense of "having to earn his pay". It means the the individual in question will not have an easy time of it or not as easy a time of it as might otherwise have been assumed. In other words, winning the race is not assured.
Altho it doesn't literally have anything to do with running, ocasionally the expression is used in connection with an actual foot race. (The origin of the phrase may have had a connection to running.)"Fortunately for the tournament, two of Woods' main rivals have been in imperious form this season and they, along with some of the rising young stars, should ensure that the short-priced favourite gets a run for the money invested in him despite the prohibitive odds."
"Daniel Martin gave Ronnie a Run for his Money this morning!"