During a formal ceremony at the General Assembly, Guterres will be sworn in before outlining in an address to all 193 UN member-states his plans.
During a formal ceremony at the General Assembly, Guterres will be sworn in before outlining in an address to all 193 UN member-states his plans to confront global crises and reform the 71-year-old United Nations.
The first former head of government at the UN helm, Guterres will take over from Ban Ki-moon on January 1, just weeks before President-elect Trump moves into the White House.
The choice of the former refugee chief as the ninth secretary-general energized many diplomats who see Guterres as a skilled politician, able to overcome divisions that have crippled the United Nations, notably over Syria.
The 67-year-old former prime minister of Portugal has put ending the five-year carnage in Syria at the top of his to-do list and is keen to put forward a new plan to achieve a settlement, diplomats say.
Trump's election however is complicating that strategy.
"This is tough for Guterres," said Richard Gowan, a UN expert at the European Council on Foreign Relations. "He enjoyed a wave of diplomatic goodwill at the UN and looked set for a straightforward transition."
"Now he will find it hard to propose big institutional reforms or float new political initiatives until the Trump team is settled in and made its intentions clear."
Trump's victory has put a question mark over the Paris climate deal championed by Ban during his 10 years at the UN helm and stirred unease over the prospect of a new-style diplomatic dealmaking from the White House that could sideline the United Nations.
Trump has not made any statements about his view of the United Nations or multilateralism since his election, but his choice of South Carolina Governor Nikki Haley as US ambassador was seen in some circles as a positive signal.
While Haley has no foreign policy experience, she has been a player in negotiating trade deals for her state and earned respect in foreign circles for taking a stand against racism by pulling the Confederate flag from the state capitol.
The key to getting the new Trump administration on board may lie in Guterres' plans for reforming the world body to "turn it into something the US can support," said a Security Council diplomat.
He will have to show that "he is shaking up the system enough in order to really make it effective, slimming it down in some places, realigning it in others, in a very pro-active way," said the diplomat, who asked not to be named.
The United States is by far the biggest financial contributor, providing 22 percent of the UN's operating budget and funding 28 percent of peacekeeping missions which currently cost $8 billion annually.
Over the past months, Guterres has toured the capitals of the powerful five permanent Security Council members - Britain, China, France, Russia and the United States - for talks on his new tenure.
"He will be a political secretary-general," said a Security Council diplomat, who was briefed on Guterres' plans. "He plans to put saving lives - peace and security issues - definitely at the center."
Guterres may on Monday announce the appointment of the deputy secretary-general and of his chief of staff - two powerful posts in the new leadership team.
Nigeria's Environment Minister Amina Mohammed is tipped to be the UN's new number two while the chief of staff post is also expected to be filled by a woman, in line with Guterres' pledge to push gender equality at the United Nations.
Over the coming months, he will make a series of appointments to head the departments of peacekeeping, political affairs and management among others, with the five council powers pushing candidacies from their countries for the plum insider jobs.