But Manning, who was slammed to the ground as he threw a touchdown pass near the end of the first half in the Broncos' 17-9 victory at Kansas City, never missed a snap after being put through the motions of concussion testing.
"I'm fine. Everything checked out OK," Manning said after the game, according to The Denver Post. "I took a hit there, but I was cleared."
It's been 14 months since Manning underwent a neck-fusion procedure that cost him all of the 2011 season and had many questioning whether he could withstand the constant pounding and punishment of another NFL season.
No problem there.
"I've got that covered," Manning said.
Manning threw for 285 yards and two touchdowns and led the Broncos down the field in the final minutes when the Chiefs were frantically trying to get a stop, setting up a field goal that sealed their sixth consecutive win.
The victory moved the Broncos to 8-3 and allowed Manning to break a tie with his boss and Broncos vice president John Elway in earning his 149th win as a starting quarterback, trailing only Brett Favre (186) for most in NFL history.
Information from The Associated Press was used in this report.