The World Professional Billiards and Snooker Association has launched an investigation into an incident during Mark Selby's 10-9 victory over Mark Williams at the Shanghai Open final on Sunday.

The inquiry relates to a snooker laid by Williams in the 17th frame.

In performing his escape shot, Selby appeared to strike the pink ball and commit a foul, although match referee Eirian Williams insisted that the red ball was struck first, ruling that no offence had been made.

"I was robbed. The referee made such an appalling decision," Williams said after the match.

The WPBSA have revealed that the result of the match will stand regardless of the result of their inquiry.