But Sheffield United boss Kevin Blackwell has confirmed the club rejected a bid from Boro (and Newcastle) for Matthew Kilgallon on transfer deadline day.
Kilgallon, who is out of contract at the end of the season, had also been a reported target for Premier League duo Birmingham City and Wigan Athletic earlier in the summer.
Blackwell: "We had two bids for Killa and I think it shows the club's intent.
"We shall be speaking with Killa again and we would have done so anyway.
"The chairman was always adamant that it would take something ridiculous for him to go and he's been true to his word."