Welterweight Brian Foster has been forced out of his scheduled UFC 129 fight after a brain hemorrhage was detected in an MRI.

"I'm sorry to all my fans but I won't be fighting in Toronto," Foster wrote on Twitter.Rift Gold "My MRI came back and [I was told I] have a brain hemorrhage! I'm so sorry."

The 27-year-old was scheduled to face Sean Pierson on April 30 at the Rogers Centre, expected to be the largest event in the promotion's history.

According to MedicineNet.com, a brain hemorrhage is a type of stroke caused by a burst in a brain artery and head trauma is a common cause of bleeding in the brain.RIFT Platinum Treatment depends on the size of the hemorrhage and the amount of swelling.

The official UFC website is reporting that Pierson will receive a replacement opponent. rift gold As of Tuesday afternoon, Pierson tells MMAFighting.com he has not yet heard of any names.

Foster (15-5), 3-2 in the UFC,RIFT Platinum is coming off a second-round submission win over Matt Brown at last November's UFC 123.