Khan (left) faces his toughest fight yet against St Clair

The former IBF featherweight champion faces unbeaten Khan at London's ExCel eager to revitalise his ring career.

But the Guyana-born Australian said: "Forget world titles, just show me the money. I don't care about the belts.

"It's just business. By beating Khan I hope to get into a position to make real money and take care of my kids."

St Clair's desire for financial security should not disguise the fact he is a quality performer, having only lost five times in his 46-fight career.

The late, great Diego Corrales, former WBA light-welterweight champion Vivian Harris and ex-WBA lightweight holder Leonard Dorin were taken to 12 rounds by St Clair, who turns 33 on the day of the fight.

St Clair, who is a replacement for the injured Martin Kristjansen, said: "This fight could put me in a position to get back to the top of the world.

606: DEBATE This is a good step up in class for Khan but with little chance of him being beaten DownDownDerbyAreDown

"Khan is a good young kid and I wish him all the best in the future but I don't wish him all the best on Saturday because I'm here to win."

Khan, 21, recognises St Clair's pedigree and is prepared to go the distance for the first time in his career.

"I've done 12 rounds in the gym a couple of times so I'm used to being in that zone," he said.

"He's better than any British fighter I could meet. It's a big challenge for me but that's what I like in boxing."

The Olympic silver medallist accepts he is unlikely to blow away St Clair in the manner he disposed of former British champion Graham Earl, a 72-second victim in December.

Khan said: "With Earl, I knew I was going to go in there and beat him. This fight, I know I'm going to win but it is a tough fight for me.

"If I'm going to be a young world champion, I need these fights and I don't just want to win it, I want to win it in style for people to notice me around the world.

"I know I've had a lot of critics saying I get easy opponents fed to me but it's me who trains hard and makes them look easy.