Chong Wei, who is also 40, told thestar.com.my that Teik Chai - who died in Surabaya, Indonesia and is survived by his wife and two sons - had been his childhood friend and that the two had planned to play together next week.

Teik Chai, whose highest world ranking was 12^th, was a men’s doubles specialist who won multiple titles before leaving the men’s national team in 2013.

He partnered Tan Bin Shen and Koo Kien Keat, among others, winning the 2004 men’s doubles title at the French International with Kien Keat.

Teik Chai won bronze with Lin Woon Fui at the 2007 Southeast Asian Games, and a year later, with the same partner, was runner-up in the Singapore Open.

In 2009 he won the men’s doubles title in the Badminton World Federation Grand Prix event in Australia, alongside Tan Bin Shen.

He also partnered Ong Soon Hock to win 2012 BWF International tournaments in Mauritius, Argentina and Brazil.

The Badminton Association of Malaysia expressed sadness at the news, and his sudden death has shocked the badminton community.

"Ah Gan was not just a friend; he was family to me," said Chong Wei.

"I will be always grateful for the countless memories we had shared together.

"We met when we were 12.

"From the classes to the training and tournaments that we competed together, every moment spent with Teik Chai was filled with laughter, joy and unconditional love.

"To Ah Gan’s family, I extend my deepest condolences."