Lee Purdy is ready to make his mark in the welterweight division ahead of his world title bout with Devon Alexander in Atlantic City's infamous Boardwalk Hall on Saturday.

Purdy is being given next to no chance against the IBF's 147lb champion having come in as a late replacement for Matchroom Promotions stablemate Kell Brook, who had to postpone a long-awaited clash with the American for a third time after suffering a foot injury in training last month.

While Colchester fighter Purdy is ranked fourth in the IBF rankings, he has a rather modest record of 20 victories, three losses and one draw as well as barely any amateur pedigree.

He has won his last four fights by knockout since losing a majority decision verdict to fellow Briton Colin Lynes in November 2011, but will need to produce one of the biggest upsets in recent years this weekend against Alexander, who also won two world titles in the light-welterweight division.

While the 25-year-old former British welterweight champion seemed to acknowledge he was a firm underdog, he warned Alexander to take him lightly at his peril.

"When you lace up a pair of gloves when you're a young boy this is what you dream of and it's come true," said Purdy.

"I'm excited for the fight, I'm ready, it's at late notice but I'm in good shape and I'll be dangerous for 12 rounds.

"We've got 12 three-minute rounds and it comes to more than just skills in the pro ring.

"You need heart, you need power, you need durability to get through a long 12-round fight and I believe I've got all of that in abundance.

"I'm ready to fight for as long as it takes. I haven't come all this way to America to let the fans down. I've come here to fight and I'm going to find a way to win."

Purdy is also unconcerned at the fight taking place on home soil for Alexander.

"When me and Devon step in that ring it doesn't matter where the ring is in the world. It's a ring at the end of the day and Devon that's going to be in front of me. I'm in great shape and ready to put a big statement out there," he added.

Alexander lamented his setbacks with mandatory challenger Brook, who delayed the initial bout in December due to an ankle complaint before the St Louis southpaw pulled out of the re-arranged contest due to a biceps injury.

The Yorkshireman's latest ailment has given Purdy the chance to shine although Alexander, who is fighting for the first time since beating Randall Bailey on points last October, is taking nothing for granted against the lesser-regarded opponent.

"It was very frustrating but I'm a firm believer in it's going to happen when it's supposed to happen. Everything happens for a reason," said the 26-year-old.

"I wanted to fight Kell Brook because he's considered one of the best at 147, I wanted to beat him but they put Lee Purdy in front of me and now I have to beat him.

"I'm a student of the game. I don't take anybody lightly. I want to send a statement to everybody at 147 that I am a force to be reckoned with and that's what you're going to see on fight night.

"Lee Purdy is coming to fight, he's hungry, he wants my title but he is just in the wrong spot at the wrong time.

"I'm in another lane and my lane is going to superstardom."