The Blues are six points clear of second-placed Manchester City with a game in hand entering this weekend's fixtures, which see Mourinho's men go to Hull on Sunday.
"We are in front, the advantage is not half a body, the advantage is significant, but still a long way to go," said Mourinho, who referred to the Blues as the "little horse" in last season's title race, when they finished third behind City.
"We are there, we are strong, we are confident
We believe in our capacity to stay there until the last match.
"We know we fight against that word you use so many times - complacency - the best way to fight is to know (there is a) long way to go."
Third-placed Arsenal are seven points behind, Manchester United eight points back in fourth and fifth-placed Liverpool are 10 points adrift of the Blues, who have won five of their last 10 in the Premier League
Mourinho added: "I think it's still five (in the title race), because the distance is still mathematically possible.
"The fifth, the fourth, don't have to fight against one, they have to overcome three.
"The distance is so short and mathematically I see that things are open."
Mourinho insists Chelsea are unfazed by leading from the front and being chased.
"It's become something normal for us this season to know that we are top of the league," added the Portuguese, pointing out the Blues have led from day one.
Chelsea are bidding for a first Premier League title in five years, since Carlo Ancelotti's side won in 2009-10.
It would be Mourinho's third Premier League title, following wins in 2005 - Chelsea's first championship in 50 years - and 2006 during his first spell.
"Chelsea won three Premier League titles and people know that number clearly, but you can analyse in a different way: in the last nine years Chelsea won it once, so it's not easy to win," Mourinho added.
"In these nine years, Chelsea was never at the end of March with six points more than second.
"We have a good situation in our hands and the way we worked last week and the way we worked this week, the players are very confident."
Source : PA
Source: PA