Shortly after the hour, Tuchel shuffled his pack, bringing on Hudson-Odoi and Alonso for Giroud and Chilwell. N’Golo Kante for Werner was our final sub as our shape shifted to 3-5-2 for the last 15 minutes, Mount and Hudson-Odoi operating in false nine roles.
Before then, Rudiger atoned for his error with a fantastic covering header to clear a threatening free-kick, and then a brave block to stop John Fleck’s shot troubling Mendy after he had danced through our defensive block.
With the clock running down, Rudiger blocked expertly again in five minutes of injury time, and in the last of those, Mendy got down low to parry a Billy Sharp overhead kick that was destined for the corner.
It was the last action of a tense and tight encounter in which Tuchel’s side showcased their ability to grind out a victory once more.
The Blues are back in South Yorkshire on Thursday night with Barnsley awaiting in the fifth round of the FA Cup. Our next league game is at home to Newcastle a week on Monday.
Chelsea (3-4-1-2): Mendy; Azpilicueta (c), Christensen, Rudiger; James, Jorginho, Kovacic, Chilwell (Alonso 62); Mount, Werner (Kante 75); Giroud (Hudson-Odoi 62).
Unused subs Kepa, Zouma, Emerson, Kante, Gilmour, Ziyech, Abraham.
Scorers: Mount 43, Jorginho 58 (pen)
Booked: Basham 17
Sheffield United (3-5-2): Ramsdale; Basham, Egan, Bryan (Sharp 68); Lowe, Lundstram, Norwood (Brewster 86), Fleck, Bogle; McBurnie, Burke (McGoldrick 62).
Unused subs Foderingham, Jagielka, Osborn.
Scorer: Rudiger OG (54)
Referee Kevin Friend