The Czech stopper didn't connect properly with a punch to allow Arsenal a simple and decisive second goal at Stevenage Borough.
It was one of those nights all goalkeepers experience - Radek kept out a penalty in the first half and made two further fine saves and, after his mistake, produced the save of the night in injury time.
Radek's response was typical of the professional. "If I make a mistake I think about going into training to make it right the next day," he said at Broadhall Way. "I have the appetite to put it right!"
It was pointed out that the words "Radek Cerny" and "mistake" didn't seem right in the same sentence
"If the goalkeeper comes out like that and doesn't take the ball then it's a mistake,"Ã‚Â he said. "The first goal I felt I got a slight touch and it was unlucky but the second goal was down to me.
"For a goalkeeper, sometimes football is hard. Football is like that.
"You can play badly and win or play very well and lose but as a goalkeeper, you can play well and still make a mistake that is very costly. Anyway, if the team loses it's bad for me and for everyone."
Radek Cerny was straight back onto the training ground after holding his hand up to his first mistake in a Spurs shirt in reserve action on Monday.