"sharp challenge" is a correct and usable phrase in written English.
You can use it to describe a difficult situation or problem that someone is presented with. For example, "John faced a sharp challenge when he had to balance his full-time job and college coursework".
Hama, the site of a 1982 massacre, has emerged as a sharp challenge to Mr. Assad's leadership in recent weeks.
The riots in poor neighborhoods across the country in 2005 were a sharp challenge to that symbolism.
In a sharp challenge to Republican lawmakers in January, President Obama circumvented Congress and opted for a recess appointment of Mr. Cordray.
UCU's independent curriculum, high academic standards and insistence on admitting solely on merit are a sharp challenge to Ukraine's educational establishment.
Mr. Zuma, 69, faces a sharp challenge from a faction that includes Julius Malema, the populist and controversial leader of the A.N.C. Youth League.
Politically, the promise of a rapid deficit abolition, returning to surplus by April 2018, was a sharp challenge to Labour: beat that!
However secular its system, it still has had sharp challenges in recent years from resurgent Islamism.
They say that older players shouldn't meet sharp challenges this way, but he is forever young, win or lose.
But in a series of unusually sharp challenges, he was repeatedly forced back to the issue of the proposed adoption ban and pressed to say if he would support it.
But many Democrats said that with Mr. Bush's approval ratings at extraordinarily high levels and the State of the Union address representing one of a president's most potent platforms, it was not a night to issue sharp challenges.
Why? "You and your interviewer have seriously betrayed your obligation to report impartially and to challenge assertions that are unsustainable" Palestine Solidarity Campaign director Sarah Colborne said: "Today presenters are known for their ferocious questioning of government ministers, their constant interruptions, their sharp challenges and refusal to brook any nonsense.
