Russell raced forward to aid his stricken colleague after Knight, playing in only his second Test, was struck on the side of the head by the full force of the ball while fielding no more than 10 feet from the bat.
Knight was taken from the field on a stretcher to one of two ambulances on stand-by at this Nottingham ground and rushed to hospital, where he was kept under observation overnight.
Amazingly, in view of the speed at which the ball was travelling after the West Indies tailender, Kenny Benjamin, met it with a full-blooded stroke, Knight did not lose consciousness.
However, Russell confessed that he feared the worst after watching Knight, who is a specialist close fielder, keel over from the force of the impact.
Russell suffered personal tragedy eight years ago when his brother, David, died from a head injury and the Gloucestershire player said that yesterday's incident brought back horrific memories. "My first thought when the ball struck Nick was that it was a bad place to be hit," he said. "My brother died after he fell over a wall and hit his head on some steps and I remembered that the blow was in the same spot."
England's physio, Dave Roberts, said Knight was being kept in overnight, which is "standard procedure with a head injury. He had an X-ray, which was clear in that there is no fracture.
"You are always worried with any head injury. There was not much distance between Benjamin's bat and Nick's head and the ball was hit pretty hard.
"There are parts of the head which are very vulnerable, but on this occasion it seems Nick was fortunate to be hit in an area where the skull is fairly solid."
Knight ducked and turned away, but could not avoid being struck after a loose delivery from the spinner Mike Watkinson, only the second ball of the afternoon session, offered Benjamin an easy hit.
There followed some anxious moments, particularly for Knight's parents, John and Rosemary, who were watching in the crowd, as a stretcher was summoned with Roberts, and the Nottinghamshire physio, Sheila Ball, attending to Knight.
The issue of protective headgear is bound to be raised again as a result. Knight was wearing only his England cap, but it is not unusual for close fielders on the off side not to wear a helmet.
More often, balls hit on the off side travel downwards and the fielder's head is not considered to be under serious threat. By contrast, close fielders on the leg side field without a helmet at their peril, with the hook and pull shots a major hazard.
Roberts added: "I think it is advisable that close-in fielders take some precautions, but I can't force a player to wear something that he feels would restrict him in doing his job."
Knight, who made a fine start to the match with a maiden Test half-century on the opening day, suffered a head injury earlier this season when he collided with his Warwickshire team-mate Trevor Penny while fielding. On that occasion he was knocked out and suffered some loss of memory, but he made a full recovery.
Miraculously, within a short time after his admission to the Queen's Medical Centre in Nottingham, he was sitting up in bed chatting to his mother and father. His further participation in the match was dependent on the doctor's report this morning.
Roberts also revealed that captain Mike Atherton was undergoing a precautionary check on the index finger of his left hand after being hit while batting.
Wes Hall, the West Indies tour manager, said: "Kenny was very upset about what happened. Nobody wants to see somebody in pain. The whole team is hoping that he will be OK."Reuse content