Despite this misfortune the car had proved to be a serious opponent for the 917.

Any serious opponents of the system would end up in prison.

But for the first time in recent years, he has a serious opponent, who seems to be campaigning harder than he is.

At this altitude and in these winds, cold has become their most serious opponent.

Napoléon found her to be a serious political opponent.

New Yorkers would expect her to spend large amounts of time campaigning in the state, even without a serious primary opponent.

Meeks hasn't had a serious opponent since his first run 1998 when he won with 56%.

"He doesn't seem all that muscular to me, and Torak's a very serious opponent."

Of course, it helped that he almost never had a serious opponent, Democrat or Republican.

To counter the mirror-image effect, we fight them as if they were actually serious opponents.