The City boss revealed that central defender Stones had sustained a leg problem at the end of Saturday’s 2-2 draw with Crystal Palace.
And speaking at his pre-match press conference the boss also confirmed that left back Benjamin Mendy was also affected by a muscular issue after the Etihad game.
Guardiola also revealed that he was closely monitoring the condition of long-term injury victim Aymeric Laporte ahead of the trip to Bramall Lane, following the French defender’s return to training after a long-term knee injury.
“John had a problem in his leg in the last action of the game and then Mendy has muscular fatigue,” the boss revealed.
Asked specifically about the chances of Stones’ figuring tomorrow night, the boss added: “I have to speak with doctors after the press conference.”
Laporte meanwhile has been sidelined after damaging his cartilage and lateral meniscus during our win over Brighton back in August but has been involved in sessions with the rest of players since the start of the month.
Asked about the chances of Laporte returning to action this week, the boss said he was monitoring his recovery on a day-by-day basis.
“Every day he’s getting better. I don’t know (when he’s back). I have to think later, tonight.”
Tuesday’s hosts Sheffield United have made an impressive impact following their promotion to the Premier League this season and gave a good account of themselves in the league game at the Etihad earlier this season.
And the boss revealed that he was full of admiration for the way that Chris Wilder’s side had gone about their business so far this season.
“I saw some moments they're doing and it’s the reason why they’re in the position they’re in,” Guardiola added.
“I’m impressed and I admire how they play with the same manager and players coming into Premier League and I like it. As a manager you see things we can improve, they’re the ones (to watch).”