A young boy suffered a suspected cardiac arrest during an under 12s football training session.
The boy was training with Penlan Football Club at the Phoenix Centre in Townhill, Swansea, on Tuesday evening.
The Welsh Ambulance Service said they were called just after 18:40 GMT to reports a person needed "urgent medical attention" - reports the BBC.
Panicked parents rushed on to the pitch and gave the boy CPR.
The boy was taken to the University Hospital of Wales in Cardiff.
The club's first team manager, posting as Crabby on Twitter, said the boy had suffered a cardiac arrest.
He said: "The young lad was given CPR by parents who brought his breath back and then was transferred to Cardiff Heath, thoughts are with all the family."
And former world boxing champion Enzo Maccarinelli said he saw the incident happen.
He tweeted: "Just seen an u12 footballer collapse on the pitch, stopped breathing."
He said parents gave him CPR and brought his breathing back.
He added: "Without doubt the most frightened I've ever been, he will be in my prayers tonight."
Penlan Juniors AFC said on their Facebook page: "Unfortunately we have to report that a young lad from our U12's has collapsed during a training session this evening.
"Paramedics were called and he is now receiving treatment at a hospital in Cardiff.
"Our thoughts and prayers are with the family and we're praying he makes a full recovery. Also to the coaches, parents and players who were incredible throughout."
Swansea City FC tweeted: "Our thoughts and prayers are with the @PenlanClubAFC U12s player who suffered a cardiac arrest during a training session last night."
