Keegan was replaced during the match, but only after playing on for several minutes after taking a knock to the head in a collision with Eoin Cadogan.
A statement, issued on behalf of manager Stephen Rochford and his team, read: “In today’s Allianz NFL Division 1 clash with Cork in Páirc Ui Rinn, Mayo player Lee Keegan was substituted with concussion symptoms.
“The Mayo medical team accept Lee should have been withdrawn as a precaution a number of minutes earlier when the collision occurred.
“Player welfare is of paramount importance to all involved with Mayo GAA and members of the Mayo medical team have been to the forefront of player welfare initiatives in the GAA nationally.
“Lee is recovering and will continue to be monitored over the coming days. As always, Mayo will follow the established Return to Play protocols.”
Speaking to Newstalk’s Off The Ball after the game, Rochford explained why Keegan wasn’t substituted immediately.
“I haven’t spoken yet with [the doctor] but he was referring that he was fine. But then quite clearly our own video analysis team and our own doc could notice it straight away. As quickly as we could get him out of the field then, we did. He was communicating at the end of the game and hopefully if there is a concussion aspect, then it’s something minor.
“The medical team were communicating with him. He was responsive in that he was communicating with the doctor. Once we were able to clearly notice that he wasn’t himself, he was pulled.”
Rochford was disappointed but pragmatic after a poor Mayo display in which the westerners went through barren spells lasting 15 and 17 minutes in either half.
And while the camp is dealing with its fair share of injuries, he still fielded eight players who were present on the team which fell to Dublin in last year’s All-Ireland semi-final.
“You go into any game looking to put in a performance, to put your best foot forward. Clearly, we were second best today,” he admitted.
“In the first half we created a couple of goal chances, we were level for the first 15 minutes. We just sat off a little bit more then and Cork got more of a grip around that middle third. They were able to supply in a better quality ball. They made hay from it. They were eight points up at half-time. If we could have kept that to a five-point game, we would have had a better chance going into the second half.
“They latched off the first five scores of the second half and really that was going to make it extremely difficult. We needed to get a goal and obviously we didn’t even create that in the second half.
“We would be disappointed, but league is league, you have got six games to move on towards in the next two months.”