The 27-year-old has not played since the beginning of last season, when he was forced to go under the knife to correct a long-standing knee issue. Without one of their key players, if not the most influential, United struggled badly last season and were relegated back to the Championship after two seasons in the top flight.
Chris Wilder the former United manager, initially expected the defender to be back available by April, but he suffered a setback in his rehabilitation.
And Jokanović, speaking to the media at a behind-closed-doors event at Bramall Lane this evening after officially starting work at his new club yesterday, said: “Jack has come back from New York.
“From the medical department I don't have any feedback that he will be ready soon to start working with me.
“Right now he is not in my plans. I don't expect him to be available for this pre-season … this is not the feedback I am getting from the medical department.”
The Scouse defender spent time in the United States this summer after working hard with a personal trainer in Dubai, being pictured pounding the boxing pads and looking in remarkable physical shape. O’Connell has previously put himself through some intensive altitude training sessions in a bid to accelerate his comeback – which can’t come soon enough as far as Blades fans are concerned.