Tottenham boss Harry Redknapp has admitted he feared the worst after seeing Fabrice Muamba being treated on the White Hart Lane pitch.
Bolton midfielder Muamba collapsed shortly before half-time in Saturday's FA Cup quarter-final clash with Redknapp's Spurs.
Medics raced to his aid after he suffered what later emerged to be a cardiac arrest.
Redknapp told Sky Sports: "When they were pumping his heart, we realised just how desperate it was. I feared the worst.
"None of us could believe what had happened. Everyone was shocked.
"I just remember him laying on the floor and my first thought was that someone elbowed him off the ball.
"Then we saw the pumping of his chest, but the medical people were fantastic, then the heart people came out of the crowd, specialists who were at the game, they came on the pitch and leant their expertise.
"They were all amazing and the crowd were fantastic, so respectful and the referee handled it so well, he was top drawer and a lot of credit to him too."
Redknapp feared he was witnessing a repeat of what happened to his former player Marc-Vivien Foe, who collapsed and died during a Confederations Cup match with Cameroon in 2003.
"Marc played for me at West Ham. That was horrendous, the lucky thing for Fabrice was that it was at a Prem ground," he said,
"If it had been a Sunday morning footballer or non-league, I do not think he would have pulled through.
"It was obviously a problem that was there so it was lucky it happened where it did as the medical people were fantastic."