The 34-year-old plans to fight in a heavyweight bout at the city’s MEN Arena on November 30 if he is granted a licence from the British Boxing Board of Control (BBBoC).
He is being put through his paces by former world featherweight champion Barry McGuigan and McGuigan’s son Shane, with his preparations set to be turned into a two-part television documentary.
Flintoff said: “This is an amazing opportunity to try a sport that I love, to be tutored by a man I respect and admire and, at the age of 34, the chance to become a professional sportsman again.
“It’s a huge challenge — probably the biggest I have ever undertaken, especially in such a short time-frame.
“I have a long road ahead and a lot of work in front of me. The stakes are high.”
Robert Smith, general secretary of the BBBoC, revealed that Flintoff had not yet applied for a licence and that the Board had not received an application for the show in question.
But as the licence application process normally lasts up to six weeks, the former England hero has enough time to apply in the near future and fight on the November date if his application is successful.
Flintoff would not be the first professional sportsman to undertake a boxing career with no experience.
Former Sheffield United footballer Curtis Woodhouse made his boxing debut in 2002 and has won 16 of his 20 contests.