When Ratchanok Intanon lifted the Singapore Open winner's shield last year for her third Superseries title in as many weeks, moving up to world No. 1 in the process, the Thai seemed unstoppable.

But a string of injuries led to a slump in form as she endured a series of early-round losses, including at the 2016 Rio Olympics.

Now, having recovered from her various ailments, the 22-year-old has pronounced herself "99 per cent" healthy and equally determined to end a year-long trophy drought with another victory at the Singapore Indoor Stadium.

"It is exciting to come back to play. I'm here to defend my title and will do my best," said the world No. 7 yesterday.

Ratchanok was seen as a medal hopeful at the Rio Games, but suffered a knee injury, and was clearly hampered in her round-of-16 loss to Japan's Akane Yamaguchi.

Her sole appearance in a final since her Singapore Open win was at last month's All England Open, in which she lost to top-ranked Tai Tzu-ying of Chinese Taipei.

"Every athlete wants to be perfect and wants to be No. 1 for a long time, but in women's singles it's unpredictable. Tai Tzu-ying is very good, she deserves to be No. 1," said Ratchanok, whose top-ranked status lasted just a week.

Her recent form has also been patchy. She was eliminated in the round-of-16 at the India Open and Malaysia Open, plagued by another injury. This time, it was her ankle.

She said: "Injury is very common for athletes. I need to recover, but now, even with my injuries, I am still able to play."

She faces an elite field - featuring the world's top eight female players - in Singapore, led by Tai and reigning Olympic champion Carolina Marin.

Ratchanok was calm about her chances and said: "I will compete round by round. From top one to 16, all the players are very close in form. It depends on whether I can perform well on that day."

Among the players who have withdrawn from this week's tournament are reigning Olympic men's champion Chen Long, world No. 3 Jan O Jorgensen, India's 2012 Olympic bronze medallist Saina Nehwal, and Singapore's Liang Xiaoyu.