At the time of going to press, the 16-year-old from Louth Old Boys team was in a "critical but stable" condition at The Diana, Princess Of Wales Hospital.
The footballer playing at London Road Pavilion, Louth, collapsed at 10.45am after being hit by the ball with some force.
Steve Pratten, divisional operations manager for East Midlands Ambulance, said this kind of accident is "rare."
"It is unusual to have a serious injury after being hit by a ball in the chest," Steve said.
"But the teenager may have an underlying condition that could have caused it.
"The ball must have been hit with some force and it is a potentially a serious injury.
"The air ambulance was used because it was the easiest and quickest way to get him to Grimsby.
"There was a lot of activity in Louth with it being the Christmas market."
One parent, who wishes not to be named, was at the match.
He said: "A lot of the young footballers were shocked.
"The injured player was given CPR by the ambulance crew.
"The games that were being played were halted as the air ambulance landed and took off.
"The game in which the teenager was playing was abandoned."
London Road Pavilion is extensively used by the local football team Louth Old Boys.
They hold their annual two-day tournament their which attracts thousands of players and supports.
