Aerospace Corp. and Space-Track.org are following the rocket as it descends.
Here are the latest estimates as to when and where the Chinese rocket will crash on Earth.
The debris from a Chinese rocket could hit Abuja this weekend.
A Chinese foreign ministry spokesperson said on Friday that the probability of any harm is extremely low, as most of the rocket components will likely to burn up upon reentry.
Remnants of China's largest rocket launched last week are expected to plunge back through the atmosphere in the coming hours, European and US tracking centres said on Saturday.
A large segment of China's Long March-5B rocket, pictured here during launch on April 29, 2021, is expected to make an uncontrolled re-entry into the Earth's atmosphere.
The rocket, said CNN worldwide correspondent Will Ripley, weighs 22 tons and is the size of ten-story building, "about a fifth the size of the Statue of Liberty, hurtling around the Earth as we speak". Because that did not happen as planned, the rocket will now make an uncontrolled reentry, and no one knows yet precisely where the debris will land.
U.S. Space Command estimated re-entry would occur at 0211 GMT on Sunday, plus or minus one hour, while the Center for Orbital Reentry and Debris Studies (CORDS) at Aerospace Corporation, a U.S. federally funded space-focused research and development center, updated its prediction to two hours either side of 0302 GMT with the rocket re-entering over the Pacific.
Pentagon press secretary John Kirby said that "this rocket debris" is "almost the body of the rocket, as I understand it, nearly intact, coming down, and we think Space Command believes somewhere around the 8th of May".
McDowell previously told Reuters there is a chance that pieces of the rocket could come down over land, perhaps in a populated area, as in May 2020, when pieces from the first Long March 5B fell on Ivory Coast, damaging several buildings.
Harvard-based astrophysicist Jonathan McDowell told Reuters that the debris could fall as far north as NY or as far south as Wellington, New Zealand.
Defence Secretary Lloyd Austin has said the United States military has no plans to shoot the rocket segment down, but suggested that China had been negligent in letting it fall out of orbit.
"We have the capability to do a lot of things, but we don't have a plan to shoot it down as we speak", Austin said.
"We're hopeful that it will land in a place where it won't harm anyone", said Pentagon spokesman Mike Howard. "Hopefully in the ocean, or someplace like that", he added. The rocket is set to be followed by 10 more missions to complete the station.