Two pilots have surpassed the world distance record for a flight in a helium balloon after crossing the Pacific Ocean. American Troy Bradley and Russian Leonid Tiukhtyaev also hope to set a new duration record.
They left Japan in their "Two Eagles" balloon on Sunday and had aimed to land in Canada or the US.
However, weather has forced them to change course towards Mexico where they are due to land sometime on Saturday.
Their hi-tech balloon is made of a strong Kevlar and carbon-fibre composite, but weighs only 220 pounds (100kg). It is fitted with monitors and other instruments that track their course and compile data to be submitted to record-keepers.
The specially-designed capsule sits beneath a huge helium-filled envelope and is designed to stay aloft for up to 10 days. The pilots live in a closet-like space with a very low ceiling.
To set new distance and durations records the team needed to beat the existing records by 1%.
For distance that meant a journey of about 5,260 miles (8,465km) to beat the existing record of 5,209 miles set in 1981.
On Thursday, the Two Eagles team tweeted: "The pilots have just surpassed the distance needed to set a new record. 5,261 miles or 8,467km."
"We're not taking any time to celebrate,'' said head of mission control Steve Shope.
"We have a lot of work we have to do, and we're just taking this flight one hour at a time."
On its website, the team says Two Eagles will not have "broken the record" until documentation is approved by the US National Aeronautic Association followed by the Federation Aeronautique Internationale - a process that could take several weeks or months.
Americans Ben Abruzzo, Maxie Anderson, and Larry Newman travelled on the Double Eagle II balloon from Presque Isle, Maine, to Miserey, France, about 60 miles northwest of Paris.
The Double Eagle II gondola is displayed at the Smithsonian National Air and Space Museum annex at Washington Dulles International Airport.
Two Eagles should pass the existing record about 15:50 GMT. To set a new record, the team must stay aloft for about 138 hours and 45 minutes.
In 1981, the Double Eagle V was the first gas balloon to successfully cross the Pacific Ocean and set the existing distance record.
Crew members Mr Abruzzo, Mr Newman, Ron Clark and Rocky Aoki made it from Nagashima, Japan, to Mendocino National Forest in California in 84 hours and 31 minutes.
The current team named its craft in honour of the existing record holders