The PTT Thailand Open announced in their website late yesterday that Rafael Nadal has been forced to withdraw from the tournament due to injury.

This is the third time Nadal has pulled out from the tournament, the last two times were back in 2006 and 2007.
In the medical certificate provided to the tournament yesterday, Dr. Angel Ruiz Cotorro, Medical Services Chief for the Royal Spanish Tennis Federation said that Nadal was suffering from an acute rupture of his right abdominal muscle, which was confirmed by an ultrasound.
The doctor added that Nadal would require, “… medical treatment consisting of physiotherapy, rest, and medication …” for a period of two to three weeks.Nadal expressed his disappointment at not being able to participate in the PTT Thailand Open.
"I am very disappointed not to be able to play in Bangkok."(Via PTT Thailand Open website)
"I was looking forward to this tournament but the injury I have been suffering during the North American summer swing needs to be taken care of."
"I am really looking forward to playing next year in Thailand where I have a very loyal and big fan base."