Mourinho is suffering from a bug and did not want to risk spreading it among his squad ahead of a pivotal week in Chelsea's season.
The Blues are at Anfield this afternoon and desperately need a victory if they are to remain in the title race.
And on Wednesday they will entertain Atletico Madrid in the second-leg of the Champions League semi-final, having drawn 0-0 in Spain last week.
Second-placed Chelsea will fall eight points behind Premier League leaders Liverpool if they are beaten at Anfield today and would be out of the hunt for the title.
But Mourinho has suggested in recent weeks that he may not choose his first-choice team, with an eye to the midweek match against Atletico.
Youngsters Andreas Christensen and John Swift have yet to play for the Chelsea first-team but have both been named in the squad.
And Mourinho has also hinted that, with first-choice goalkeeper Petr Cech already injured, he may not be willing to risk Mark Schwarzer.
Third-choice keeper Hilario will be between the posts if Schwarzer is rested.
Watch Liverpool take on Chelsea live on Sky Sports 1 at 2.05pm