Suu Kyi took office last year as Myanmar's first civilian leader after 50 years of junta rule.
She has since focused her energy on the delicate political dance between her civilian government and the generals who still hold many of the levers of power.
On Tuesday the Nobel laureate will give the biggest speech of her time in office.
The nationally-televised turn will break a near silence since the ulcerous ethnic and religious hatreds in western Rakhine state erupted into killings on August 25, sending 400,000 Muslim minority Rohingya fleeing into Bangladesh.
Some 30,000 ethnic Rakhine Buddhists and Hindus have also been internally displaced.
In an interview with the BBC, UN Secretary General Antonio Guterres said the stakes were high for Tuesday's speech, calling it a "last chance" to stop the unfolding humanitarian calamity.
"If she does not reverse the situation now, then I think the tragedy will be absolutely horrible, and unfortunately then I don't see how this can be reversed in the future," he said.
The latest violence was sparked by Rohingya militants' raids on 30 police posts in Rakhine state.
The UN calls the army fightback a "textbook example of ethnic cleansing" with villages set ablaze to drive Rohingya civilians out.
Many abroad are puzzled as to how rights can be flagrantly denied to a specific group by a people who once nobly demanded their own in the face of a junta.