Rafael van der Vaart has described Fabrice Muamba's collapse at White Hart Lane as "the absolute low in my football career".
The Tottenham playmaker was among those seen praying on Saturday evening as medics rushed onto the pitch to tend to Muamba.
The Bolton midfielder is currently being cared for at the London Chest Hospital after suffering a cardiac arrest, with his condition stable but still critical.
Van der Vaart has spoken for the first time about the events which unfolded around him during the abandoned FA Cup quarter-final clash, and the Dutchman is still coming to terms with what happened.
He told Spurs' official website: "It's almost incomprehensible what has happened.
"(It was) simply horrifying to see such a young player on the ground struggling for his life.
"I was standing about 10 metres from him but I didn't see him fall. It happened behind my back, but when I turned I immediately knew things weren't good.
"At that time all players on the field felt the panic as well. It was horrible to witness, it's the absolute low in my football career.
"I'd like to express my sincere support to the family, team-mates and everyone who is involved with Bolton Wanderers.
"Fabrice, we'll keep praying for you and I hope with all my heart that everything will be all right again."
Spurs left-back Benoit Assou-Ekotto has also given his reaction to the incident.
"Saturday was one of those days that will stay with me forever," Assou-Ekotto wrote in his London Evening Standard column.
"When I saw him lying on the pitch at White Hart Lane, I was scared. Scared for him, scared for his family, his friends and all those people who know him and who care about him.
"I was also scared because he was just like me. He is young, supposedly fit - an athlete - who a few seconds ago was running up and down the same pitch as me. I had flashbacks of what had happened to my countryman, the late Marc-Vivien Foe.
"You want to stop these thoughts but the pictures keep coming into your head and I must say I was scared. Scared as I wondered how it could all just end like that for a young man? I could see the same questions in the eyes of my team-mates, the Bolton players, our bosses and their colleagues."
