Due to early round exits in 2013 and a four-year title drought, Koo parted with the Badminton Association of Malaysia and became a coach for the Granular Club of Thailand in early 2014. In August that year, Koo returned to play his last tournament with Tan at the 2014 BWF World Championships. Their last match together was in the third round where they lost to a Chinese Taipei pair with a score of 19-21 in the deciding game.
Koo Kien Keat moves very fast around the net areas and is adventurous with deceptive shots. He also reacts very well on fast flat exchanges. A favourite formation is when he is on the front court and his partner, the main smasher, attacks from the rear of the court with powerful, left-handed smashes.
Kien Keat and Tan Boon Heong are an explosive and dynamic pair in their game style.
In 2010, they won their first title of the year in their home, Malaysia, as the world number 1 pair. They came in seeded number 1 in the All England but lost in the first round to Denmark former world champions Lars Paaske and Jonas Ramussen.