Donald Trump will make a surprise trip to Mexico to meet the country's president hours before delivering a highly-anticipated speech on immigration.
The Republican White House candidate said on Twitter that he looks "very much forward" to meeting President Enrique Pena Nieto.
The Mexican leader had invited both Mr Trump and his Democrat rival Hillary Clinton to visit Mexico.
Mr Pena Nieto and Mr Trump will meet in private on Wednesday.
Mr Trump has made illegal immigration and his call for a wall along the US-Mexico border a centrepiece of his presidential campaign.
Mr Pena Nieto has been sharply critical of Mr Trump's insistence that Mexico would pay for the border wall.