Almost a year after Singapore Airlines (SIA) axed non-stop flights to the United States, rival carriers like Cathay Pacific and Korean Air have been boosting services and growing market share.
This has given other airports in the region an edge over Changi when it comes to Asia-US air links, said analysts.
"With the reduction in flights, there has been some impact on Changi as other airlines in other airports have added services to the US," said Mr Shukor Yusof of aviation consultancy Endau Analytics.
From 1.09 million one-way seats from Singapore to the US last year, SIA will offer an estimated 935,489 seats this year, based on data compiled by British aviation consultancy firm OAG.
Hong Kong's Cathay Pacific, on the other hand, will provide 1.11 million seats this year, up from 897,423 last year.
Four years after launch, SIA scrapped its non-stop services to Los Angeles and New York late last year due to weak demand and high fuel prices.
Today, it operates four daily flights to the US - one to Los Angeles via Tokyo, a service to New York via Frankfurt and two flights a day to San Francisco, via Hong Kong and Seoul.
SIA also flies five times a week to Houston, via Moscow.
The US market is important, said Changi Airport Group's spokesman Ivan Tan.
Even though it makes up less than 5 per cent of overall traffic, "it was essential for Changi to maintain and grow the Singapore-US sector due to important business trade links between the two countries", he said.
Changi will continue to work closely with airlines and other partners to encourage carriers to use Singapore as a stopover for their US flights, he added.
For example, the airport has worked with SIA and United Airlines on marketing programmes to promote stopover and transit via Changi, he added.
The airport has been working closely with Delta Air Lines, which rerouted its daily service from Minneapolis to Singapore via Tokyo, to leave from Seattle.
But more is needed, said experts.
Changi should try and convince Delta to fly non-stop between its hub in Seattle and Singapore, said analyst Brendan Sobie.
Such changes are needed, said analysts, because Changi Airport and SIA are facing increasing competition from Asia-Pacific and Middle Eastern rivals.
In April last year, Qantas stopped using Singapore as its hub for flights between Australia and Europe, choosing to stop over in Dubai instead as part of a partnership with Emirates.
For travellers like laboratory manager Tay Wanyi, 56, who still prefers to fly SIA when she travels to the US, mainly for work, the more links and flight options, the better.
She is prepared to pay a premium for better service and space.
"I believe that there are passengers like me who will be prepared to pay up to 50 per cent more than the standard economy fare for more spacious seats," she said.