"I can see you don't believe me a credible opponent in unarmed combat," Sen said.

A big problem for his boxing future is the scarcity of credible opponents.

"There's big money that will come to any credible opponent."

It would be easy to endorse Hillary Clinton for a second term even if she had a far more credible opponent.

"But he's a big strong guy who's undefeated and he's a credible opponent."

But he's a controversial guy, and as such he should have generated a credible opponent.

His fellow party members can speed that day by fielding a credible opponent.

Nonetheless, for the first time since 1977, Koch is confronting credible opponents.

Shimkus has only faced one credible opponent since his initial reelection, in 2002.

The Brazilian football team will finally meet a credible opponent when they play the Germans tomorrow.