Richardson, from Colchester, outscored Protkunas 60-54 in his first fight since leaving the amateur ranks and did not find the extra distance a problem.
“It was the first time I’d done six rounds. As an Olympic athlete, it’s a bit more of a sprint, three three-minute rounds. (But) I pride myself on being fit as a controllable factor, I’m very diligent in my approach to preparation and training,” he said.
It is just over a year since Richardson won bronze at the Paris Games, Team GB’s only boxing medal, and he is still finding it difficult to leave his experiences in the French capital behind.
“Every single day it feels like the Olympics is a topic of conversation. It’s one of the only times the country gets behind their own and you feel that pride to be British. We don’t get that enough in the country,” he said.
“I certainly felt that during and post the Games. A year on people still talk to me about it and I think that just shows the impact and the power of sport.
“People think it was an overnight success, it wasn’t. It was years and years of hard work and discipline, with a lot of setbacks along the way.
“The average person may have quit or looked to go on a different path so I guess it’s testament to me and my team for sticking to the process.”
Richardson – who signed to Frank Warren’s Queensberry Promotions stable when he turned pro in May – is hoping that fighting in the Greater Manchester area on Saturday will enable him to add some extra followers to his fan base.
He added: “The Games helped to bring that national focus on me. Of course I want to represent Colchester and Essex but when we move on to world honours, I want to represent the whole of the UK.”
Lewis Richardson was speaking to BBC Essex’s Tom Larsen-Wright