League Two high-flyers Port Vale have given Sheffield United permission to talk to their boss Micky Adams over the managerial vacancy at Bramall Lane.
"We have received an approach and have reluctantly allowed Micky to speak to them," said Vale chairman Bill Bratt.
Doncaster boss Sean O'Driscoll played down suggestions on Thursday that he has accepted the Bramall Lane post.
The Blades said they would not appoint a successor to Gary Speed, who took up the Wales vacancy, until the new year.
First-team coach John Carver has been placed in caretaker charge of first-team affairs as Sheffield United look to find a full-time successor to Speed.
"Micky is a terrific manager who has been up front and honest with us throughout the process. It's testament to how well he's done at Port Vale that we have now been approached," Bratt added.
"Micky was offered a new contract before this happened - and that is still on the table.
"We obviously want him to stay and we know everyone connected with the club feels the same."
O'Driscoll, meanwhile, has played down speculation that he is about to move across Yorkshire.
"I am not part of the process of Sheffield United appointing a new manager," he told Rovers' official website.
Doncaster chairman John Ryan said he expected the 53-year-old to be loyal to the club.
"I've been loyal to Sean over many years and he has been loyal to me and I expect it to stay just the same," Ryan said.
"United have got the fan base, they have got the stadium but we have got the team and that can count for a lot."
Ryan also told BBC Radio Sheffield that if O' Driscoll were to join the Blades the fans would have to be patient.
"If he went to Sheffield United he would be their greatest manager but whether they would give him the time is one thing, and he might end up relegating Sheffield United because it takes time for his system to work," Ryan added.
Rovers would also demand a big compensation fee, estimated to be at least 500,000, should O'Driscoll decide his future lies at Bramall Lane halfway through the season.
Speed, who was only in charge at Bramall Lane for fourth months, was appointed manager of Wales on 14 December, leaving United only a point above the relegation zone.
However on Saturday the Blades beat Swansea City 1-0, giving the club a four-point cushion. After the match Carver dedicated the win to Speed, and if he oversees a continued improvement in form the caretaker could be in a strong position to get the job on a permanent basis.