'Apprentice' winner Joseph Valente quit working with Lord Sugar in order to regain control of his boiler installation firm.
Joseph Valente won the BBC show in 2015
The 35-year-old TV star walked away from his high-profile business partner after just two years, amid growing frustrations with their working relationship.
Joseph - who won the BBC show in 2015 - told The Sun newspaper: "Lord Sugar was my idol. As a young man I worshipped him. I’d been an 'Apprentice' fan for many, many years before I went on the show.
"But after a while it became quite a frustrating relationship."
Joseph initially wanted Lord Sugar to act as a "coach or mentor". But the pair soon developed a tense working relationship.
He shared: "I was looking for a coach or mentor who was going to teach me how to grow my business.
"Those meetings with Lord Sugar were very fiery. There was quite a lot of shouting and debating going on.
"That’s the fun part of a board meeting, really. As a young entrepreneur I thought Lord Sugar would be an expert in all business, but he is an expert in his field.
"It seemed to me he had limited knowledge of my industry."
Joseph sold his boiler installation firm, ImpraGas, in 2020, after it experienced some financial troubles.
But the TV star has subsequently found success selling "online training courses", after a social media post from Lord Sugar spurred him into action.
Joseph shared: "What sparked me into action was Lord Sugar. He shared one of the articles, ‘Joseph’s Gas Firm Blown’, and retweeted it saying, ‘You can’t win them all...
"That hit me deep. It was like a right hook when I was already in a bad place. But I tell you now, it gave me the fire to get up.
"I saw the tweet, jumped out of bed and said, ‘Right, I’m going to show you I can come back’.
"It gave me another spark and another point to prove to Lord Sugar. I’m grateful to him for almost mocking me because it made me very angry and I used that emotion to fight back."