Energy drink entrepreneur William Storey says he has launched a bid to buy Sunderland.
Current owner Stewart Donald, who resigned as Sunderland chairman last weekend, is keen to sell the Sky Bet League One club.
Storey, the CEO of Rich Energy, revealed the news of his bid via Twitter on Friday.
"I am limited in what I can say due to NDA (Non-Disclosure Agreement), but I can confirm that I have made a formal legal offer for SunderlandAFC," he wrote.
"I have significant funding from blue chip backers. Sunderland are a giant of English football & their fans deserve a team to reflect that stature."
Sky Sports News have been told Storey is yet to prove funding is in place, while Sunderland remain in talks with a number of groups over a potential sale of the club.
Donald, who reiterated his desire to sell Sunderland last weekend, is looking for £35m for the club he bought two years ago.
The British businessman promised not to "outstay his welcome" when he took over from Ellis Short in 2018.
Sunderland failed to achieve their objective of promotion from the third tier in each of his two seasons as owner, something Donald has taken personal responsibility for.
"Holding this position has been a privilege, and not one I have given up lightly," Donald said in a club statement following his resignation as chairman.
"Results and performances on the pitch have simply not been at a level befitting of Sunderland's history and potential.
"I fully recognise that has caused immense hurt and, ultimately, the buck for the club starting a third successive season in League One stops with me."