Tottenham will be without leading striker Harry Kane for the visit of Liverpool who have won 19 and drawn one of their 20 league games so far and lead the table by 13 points.
Kane is ruled out until April with a hamstring tendon injury that requires surgery and Mourinho is also without midfielders Moussa Sissoko and Tanguy Ndombele while goalkeeper Hugo Lloris is still out following elbow surgery.
Tottenham have won only once in their last four league games after initially enjoying a bounce when Mourinho replaced sacked Mauricio Pochettino -- hardly encouraging with the Liverpool juggernaut heading to north London.
"They are the best team in our competition, just to say that -- I could say more," Mourinho said of Liverpool. "It's a big challenge for us to play them.
"We would prefer to play against them with everybody available, prefer to have more options.
"We have injuries but I have to focus on what we did in the week, concentrate on the effort and enthusiasm the boys put in this week and the motivation you need to play the best teams.
"If you are not confident, it's better to stay at home. If you're confident it's not going to be easy but if you're confident you're going with everything that you have and that's what I want the boys to do, go with everything we have."
Mourinho described Kane as "irreplaceable" and said Sissoko has been has been one of his "best performers" since taking over, but despite the setbacks he prefers to look at the positives.
"Good news is that before the end of the month we have two new players, Hugo Lloris and Ben Davies. This is good news," he said of the imminent return of keeper Lloris, who has been injured since Mourinho took over, and left back Davies who has made only one appearance in that period.
"I don't want to speak about Harry because if I speak too much I get depressed, and then you say I'm miserable and in a bad mood. It's better to speak about things that make me laugh."
While Son Heung-min has performed admirably as a striker in Kane's previous injury lay-offs, Mourinho said he will effectively be without a recognised forward against Liverpool.
"We don't have another one. There is not a striker in the squad. We have only one, he is not fit, we don't have another one," Mourinho said.
Mourinho played down suggestions Tottenham could sign a replacement this month.
"January is a difficult market," he said. "If the (chairman) arrives with a solution that can help us to face this difficult months ahead of us then it's welcome.
"But if we don't find the right solution the right opportunity then we are going to wait for next summer. Let's be calm, my focus is totally on the players we have available."
By Martyn Herman
