Tito Vilanova’s side wrapped up their ninth victory in a row with a 4-1 win at home to second-placed Atletico Madrid, while at the Bernabeu Juan Albin’s 88th-minute equalizer ensured Espanyol took a share of the spoils.
Sergio Garcia had given the visitors the lead after half-an-hour before goals from Cristiano Ronaldo and Fabio Coentrao seemed to have set Real on the way to victory.
However there was still time for Albin to shock Los Blancos late on, leaving Mourinho pessimistic about his side’s chances of lifting the title for a 33rd time.
"I think it is almost impossible," he told reporters after the match. "What we have to do is play every match to win without worrying about whether we are first, second or third or whether our direct rivals won or lost."
The result only adds to the pressure on the Portuguese and although the club’s president Florentino Perez defended him in the week, describing him as "the best coach in the world", Mourinho acknowledges their performances are not have not been as good as they should be.
"We just have to try to improve and win matches. If we improve in the league it will help us improve in the cup and the Champions League," he said. "If we want to have a chance in these two competitions we have to be stronger.
"I’ve never seen a situation like this where I have lost that many points and my team was so far from its aims, in this case the league. It is a new situation for me but I do not make a big drama about it. It is a new stage in my career and I will try to do my best.
"I do not lack the strength to try my best until the end of the season. We have titles to fight for. The league title seems almost impossible, but we must continue because Real Madrid demands that pride and professionalism to always try to do your best and to win.
"But in all my years of coaching we have always, or almost always, met our targets and therefore this is a new situation for me."