Marouane Fellaini joins Manchester United's injury list ahead of the Premier League match against Huddersfield at Old Trafford.
The Belgium international came off seven minutes after being brought on in the midweek defeat at Tottenham and faces a spell on the sidelines with a knee injury.
That first defeat in 10 in all competitions for United leaves them 15 points behind Premier League leaders Manchester City, with Mourinho conceding the title may well be heading back to United's bitter rivals.
"It's important for us because we need points to be the first of the last," Mourinho said. "We need to try to finish second."
At home, United remain a dominant force, though. United have lost just two of their last 39 Premier League home games, with both of those defeats coming against City.
Despite not tasting league success since the beginning of December, Huddersfield will travel west to Manchester in hopeful mood, having earned a first win over United since 1952 with a 2-1 victory at the John Smith's Stadium back in October.