Detroit Lions running back Jerome Harrison had surgery Friday after a brain tumor was discovered during a physical on Wednesday for a trade with the Philadelphia Eagles that was nullified because of the condition.

Lions head coach Jim Schwartz said that Harrison was placed on the reserve/non-football illness list on Friday. Schwartz visited Harrison at the hospital, and several teammates said they plan to do the same soon.

He was in very good spirits, Schwartz told the Detroit Free Press. But, after that, I don't know if I want to talk too much. It's one of those things, it's a non-football thing, and I'll just let him take it away from that spot.

Harrison complained of headaches to the Eagles team internist, Dr. Gary Dorshimer, during Wednesday's physical, according to CSNPhilly.com. The doctor ordered an MRI that revealed the brain tumor, which necessitated prompt surgery.

A handful of players told the Free Press that Harrison had complained of headaches, to the point of wearing sunglasses on the sideline until he was fitted with a visor for his helmet.

Everybody thought it was just a regular headache, said Lions cornerback Chris Houston. It was much more than that.

It has been said that the trade and subsequent discovery of the brain tumor might have saved Harrison's life. Harrison is not expected to play again this season, but his long-term prognosis both for life and his football career appear to be good, according to sources.

You don't really think about a brain tumor, said Lions linebacker Isaiah Ekejiuba. You think about maybe a hard hit to the head, migraine, maybe a few days to get back and clear your head up, but you see how serious it can be.

The team signed Eldra Buckley to the practice squad as Harrison's replacement.

Harrison and an undisclosed 2013 draft pick were supposed to be traded to the Eagles on Tuesday for running back Ronnie Brown.

Buckley worked out for the Lions Thursday and practiced with the No. 1 punt team Friday, according to the Free Press. He could be active because starting running back Jahvid Best is officially out for Sunday's game against the Atlanta Falcons due to a concussion.

Cornerback Eric Wright tweeted late Thursday night that he was visiting Harrison in the hospital.

Chilling at the hospital wit JC... This dude is a beast, Wright wrote. This dude got me rolling right now.. Smh he gone be juuusst fine.. #Blessings.

Maurice Morris is expected to start in Best's place against the Falcons, with Keiland Williams as his backup.