Lin Dan is regarded as the best badminton player of all time, but his dominance is on the decline and Chinese fans and media are readying his career obituary.

Widely known as "Super Dan" during his heyday, the 35-year-old lost in the opening round of the Hong Kong Open last week - the ninth time in 19 tournaments this year he has lost in the first round.

Still, the former world No 1, who has won every major prize in badminton - some of them multiple times - appears determined to go for a third Olympic title at the 2020 Tokyo Games.

By then, badminton's answer to Roger Federer will be nearly 37, but unlike the Swiss tennis great, all the signs are that Lin is already well past his prime.

Each country can send a maximum of two men's singles players to the Olympics, and Lin is currently ranked 13th in the world, below compatriots Shi Yuqi and Chen Long.

"It all depends because there are very many strong players in China," Lin said of his chances of making it a grand career finale in Tokyo.

"They're very strong so I have to be on top of them," Lin, a fiery and controversial character down the years, said after losing to Japanese world champion Kento Momota in Hong Kong.

Lin's long list of achievements include five world titles between 2006 and 2013, back-to-back Olympic golds in 2008 and 2012 and six All England crowns.

In 2011, he became the first player to complete the 'super grand slam' of badminton's nine major titles.

Lin's victories are often accompanied by exuberant celebrations when he rips off his shirt and gives a military salute to the crowd.

But he has won just one tournament this year, the New Zealand Open in May.

Some Chinese media have taken to calling him "First-Round Lin" because of his now common early exits in competitions.

He was bestowed the same unflattering label at the start of his career, before he fulfilled his potential.