Lufthansa is close to placing an order, split between Airbus and Boeing, for dozens of long-haul jets, two people familiar with the matter said on Friday.
The keenly awaited order, due to be announced next week, follows a contest between the planemakers for roughly 50 aircraft to renew the German flag carrier's long-distance fleet.
It is expected to include the first public commitment to buy a revamped 400-seat version of Boeing's 777 mini-jumbo, code-named 777-9X, which the planemaker aims to launch this year.
The 406-seat Boeing 777-9X, equipped with new engines and wings, is expected to start flying passengers around the end of the decade.
Lufthansa is also expected to order an estimated 20 to 25 of the smaller Airbus A350-900 aircraft. The 314-seat model is due to enter service in the second half of next year.
A Lufthansa spokesman confirmed the airline was holding talks.
"We are in intensive negotiations with manufacturers about ordering long-haul jets," the spokesman said.
"The negotiations are ongoing and no decision has been made. Once a decision has been made, the management will pass the matter to the supervisory board for a decision; that has not yet happened."
Europe's Airbus, a division of EADS, and U.S. rival Boeing both declined comment.
Reuters reported last month that Lufthansa's supervisory board would meet on Sept. 18 to review a potential order worth more than $10 billion.
Lufthansa said it does not comment on the timing of board meetings.
In March, Lufthansa approved purchases of 108 smaller aircraft, dominated by a 100-plane order for medium-haul planes awarded to Airbus.
A senior executive told Reuters the following month it would consider buying several dozen wide-body jets, but would not necessarily cover all its requirements in a single order.
The airline has also expressed interest in the 787 Dreamliner despite the aircraft's recent technical problems.
The Lufthansa group, which includes Swiss and Austrian Airlines, has a reputation for exhaustive technical analysis and is seen as a key battleground as Airbus and Boeing vie for advantage in one of the most lucrative parts of the market.
Europe's largest airline group aims to update a varied fleet including some ageing Airbus A340 and Boeing 767 planes.
Lufthansa's fleet has no 777 passenger planes. Its cargo operation has five 777 freighters on order, with the first delivery due in October. Lufthansa's Austrian subsidiary already flies 777 passenger planes and its Swiss unit has six on order.
Dreamliner 787-9 prepares for takeoff
Meanwhile, Boeing said on Friday that its high-tech Dreamliner 787-9 aircraft will make its first flight as soon as Tuesday.
The flight-testing schedule may change due to weather conditions or other factors, the company said.
Reuters reported on Thursday that the test flight was planned for next week.
This story has been updated to reflect that Swiss 777s are not yet in fleet.