Tottenham Hotspur attacker Rafael van der Vaart has been reflecting on the moment when Bolton Wanderers midfielder Fabrice Muamba collapsed during Saturday's FA Cup tie at White Hart Lane.
It has since been confirmed that Muamba suffered a cardiac arrest and is currently in a critical condition at the London Chest Hospital in Bethnal Green.
Van der Vaart, who was near the 23-year-old when he fell to the floor, has described the incident as the "absolute low in my football career".
"It's almost uncomprehensible what has happened," Van der Vaart wrote on his official website. "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, teammates and everyone who is involved with Bolton Wanderers. Fabrice, we'll keep praying for you."
A number of footballers took to Twitter over the weekend to offer Muamba their support.