INDIANAPOLIS (AP) _ Indianapolis Colts fullback Craig Heyward underwent more than 12 hours of brain surgery Thursday to remove a benign tumor from the base of his skull.

Heyward was taken into surgery about 8 a.m. and was still in the operating room 12 hours later, a Methodist Hospital spokeswoman said.

``He's still in surgery and it looks like it might be another hour or two'' before neurosurgeon Troy Payner finishes, said Methodist spokeswoman Jennifer Farley.

Farley said Payner, a vascular and skull base specialist, isn't expected to discuss the surgery or Heyward's prognosis until Friday morning.

The tumor was detected by doctors after Heyward, 32, complained of blurred vision in his right eye. He underwent an MRI and CAT scan, and tests showed the tumor was pressing on the optic nerve.

Heyward, who is in his 11th NFL season, joined the Colts last month in an effort to help turn their season around. Those efforts ended when doctors discovered the small growth last week.

As Heyward was undergoing surgery, his well-being was on the minds of his Colts teammates, who practiced Thursday at the team's complex to prepare for Sunday's game with the New York Jets.

``You have to go on, but we are very concerned,'' tight end Ken Dilger said. ``We're all thinking about him and hoping for the best. Something like this makes you realize there are things much more important that football.''