Speculation is rife that the Portuguese will elect to field "the kids" for the trip to Merseyside, with a Champions League semi-final with Atletico Madrid looming large.
However, Johnson - who played under Mourinho in West London - has urged his teammates to laugh off his former manager's comments ahead of the top-of-the-table encounter.
He told reporters: "To be honest, it isn't important. We have got to worry about ourselves and concentrate on our own job.
"And if we play like we did against Manchester City we can beat anyone. I don't see much of it, if I'm being honest, but I can just laugh it off because that is what they do.
"Their situation is different at the minute, as they are in-between Champions League games. We don't know what their priority will be or what Mourinho is thinking. You try to ignore all that."
Kickoff tomorrow is scheduled for 2.05pm.