Mark Duffy has become the latest Blade to sign a new and improved long-term contract.
The experienced playmaker has agreed fresh terms and put pen-to-paper on a deal until the summer of 2020.
The 32-year-old was instrumental in United's record-breaking, title-winning campaign last season, making 44 appearances in all competitions and this season his form has reached new heights in his 25 outings to date.
Boss Chris Wilder remarked: "Mark's always stated that he sees his future here and I'm delighted that a coveted player wants to extend his stay.
"He adds to our options at the top of the pitch and has done fantastically well this season, having Mark in the building strengthens us and this rewards him for a really good first part of the season at Championship level."
Duffy follows John Fleck, David Brooks, Jack O'Connell and Leon Clarke in penning deals since the season begun in August. Prior to that Billy Sharp, Chris Basham, Kieron Freeman and Paul Coutts all signed new contracts.