The Spaniard has been a huge hit since signing from Real Madrid for £27.5m in the last summer transfer window. However the left-back has been struggling with illness.
"The good thing is I don't think we have injuries from the match today and Reguilon trained this morning at the training ground so normally tomorrow he will be fine," said Mourinho in his press conference.
Reguilon has made seven appearances for Tottenham in all competitions so far this season, and has provided three assists.
Elsewhere, Mourinho is expected to make numerous changes to the side that brushed Bulgarian outfit Ludogorets aside on Thursday in the Europa League.
Giovanni Lo Celso is expected to drop down to the bench, with Son Heung-Min stepping in as his replacement.
Ben Davies will likely be replaced by Reguilon at left-back.
Harry Winks is also set to give way to the returning Tanguy Ndombele.