Boeing Co. is considering stretching its largest 777 model to create a twin-engine aircraft in an attempt to rival Airbus Group SE’s ailing A380 superjumbo jet, sources told Bloomberg.

The Chicago-based airplane manufacturer has had private talks with several carriers about the so-called 777-10X, including Emirates, the world’s largest operator of both Boeing’s 777 and Airbus’s double-decker plane, the report said.

The new model is expected to carry about 450 passengers while the Airbus’ A380 can carry between 489 and 517. But to accommodate the 450 people, Boeing would have to stretch the frame of its 777-9 to add in at least four extra rows of seats. The 777-9, which will be unveiled later this decade, will be the first twin-engine model to encroach on the jumbo territory capable of ferrying 400-425 passengers and Boeing's most expensive product so far.

“We are always evaluating technologies, airplane configurations and market needs,” Boeing spokesman Doug Alder reportedly said. “While no decisions have been made, we will continue to study 777X derivatives and seek customer input to develop products that provide the most value for customers.”

The report said that an Emirates representative wasn’t available for comment. A source, however, told Bloomberg that Emirates reviewed the new 777 model but wasn’t quite sold on the concept. The carrier has ordered 289 jets from Boeing’s 777 series, including 150 of the upgraded versions known as the 777X. Two years ago, Boeing pitched Emirates on its 747-8 jumbo as a potential A380 replacement but was unsuccessful.

Boeing is hunting for an advantage while the uncertainty over the future of the A380 and strain in Airbus’ relationship with Emirates still exists. The Gulf carrier has been pressing Airbus to upgrade its engines to bolster fuel savings but the European aircraft manufacturer has been reluctant to make the multibillion-dollar investment for one customer.

Emirates President Tim Clark told Bloomberg earlier that talks with Airbus to upgrade the A380 engines have lapsed. “My main concern is that they stop producing the plane,” he said.

Boeing is looking to expand its current product line-up into new market niches. The company is also looking to redesign its smallest 737 Max. With sales of Airbus’ A380 and 747 starting to falter, stretching the already jumbo 777-9 may attract potential consumers to Boeing. The A380 saw a two-year drought in sales that was finally broken in 2016 when it nailed two big deals with Japan's All Nippon Airways and Iran Air in one week.

Sales of Boeing’s 777X have also slowed since the airplane manufacturer unveiled the plane at the Dubai Airshow in November 2013. The upgraded planes will feature Boeing’s largest-ever wingspan with tips that fold up when the plane taxis around airports. Boeing’s last sale came more than a year ago when an unidentified customer ordered 10 of the planes. Cathay Pacific and All Nippon Airways are also customers of the aircraft.