In this universe, the trickiest challenge of all is survival.

But its strategy means that Xerox must manage two different businesses, and that promises to be a tricky challenge.

And advertisers and publishers alike concede that selling to the older market is a particularly tricky challenge.

Ms. Goldberg gives a lovely, measured performance as a woman rising to a tricky challenge.

"Muslims in Europe: integration is tricky challenge."

Dealing with the railroads has been an even trickier challenge for the administration because the railways are regulated by the federal government.

It is a tricky challenge for the actor playing the title character because he must undergo a personality transformation offstage.

Choosing a movie that will please a wide range of people in a party situation is a fun but tricky challenge.

But it also meets a trickier challenge, that of being superb entertainment.

Replacing Johnson's confidence, excitement, passion and influence - championship-minded ingredients - is a much more tricky challenge.