"I am not quitting; instead I will move up to the lightweight division," he said. "There are titles still to be won at lightweight. I have been a junior lightweight fighter for a long time. That took a toll on me. I might be short but am big.
"People can say what they like and I don't care."
He said it was natural for boxers to outgrow their natural weight divisions .
"Dingaan Thobela started as a junior lightweight; went on to fight at junior welterweights and ended up winning the WBC title in the super middleweight division. Some may say at 37 what am I still doing in boxing but my response is Bra Jake Matlala went on to become the greatest when he was well over 37 years," said Klassen who looks a million dollars on a good night.
But what Klassen - who has over 40 fights - did against 10-fight Fuzile is unforgivable. He held up his hands and quit 51 seconds into the fourth round.
"I will get my spark back," he said. "I spoke to my trainer Bernie Pailman and he agreed that I still have fire in me. And also I still look the same way I was 15 years back. I do not know the pain of being knocked clean cold. Yes I have two stoppages on my record. Watch the space."