UFC Welterweight fighter Thiago Alvez successfully underwent an 8-hour brain operation at a New York City hostpial today, according to TMZ.com.

The operation was to separate an artery from a vein in his brain. Alvez was scheduled to fight at last weekend's UFC 111 pay-per-view, but was forced to pull out of the fight after a CT scan of his brain discovered the issue that led to today's rugery.

UFC President Dana White told Dana White that the operation was a "complete success."

The Pitbull's first words after getting out of surgery ... "When can I start training again?"

Alvez will be in ICU for the next two days and is expected to make a full recovery and be training again in a month or so.