Chelsea have dropped points on just five occasions so far this season in the Premier League and sit three points clear of second-placed Manchester City ahead of their trip to north London.
However, their four draws and solitary defeat have all come on the road, with Sunday's 1-1 draw with Southampton representing the most recent setback.
City were unable to capitalise on that result as they threw away a two-goal lead to draw at home to Burnley.
When it was put to him that Chelsea's away form could see them caught by City during 2015, Mourinho stated his team were simply going through a tricky run of fixtures.
"We had very difficult fixtures away from home. We lost one game [against Newcastle United] that we didn't deserve to lose," said the Portuguese.
"We are doing well. Every match is difficult. When we go to Tottenham it's difficult, when we go to Swansea it's difficult, when we go to QPR it's difficult, I don't think there are easy matches.
"At the end of the season there are 19 matches at home and 19 matches away. Of course it's more difficult now, we have a difficult period, other teams have an easier one.
"But if it's a draw [that decides the fixture list] it's a draw, you cannot complain with a draw."
Chelsea boast an impressive home record against Spurs in the Premier League but drew at White Hart Lane last season and required John Terry's second-half goal to snatch a point.
Like Mourinho, Spurs boss Mauricio Pochettino has a full squad to choose from, with Nabil Bentaleb set to return from illness for a side that have found form of late.
Unbeaten in the league since December's 3-0 defeat to Chelsea at Stamford Bridge, Spurs have taken 11 points from their last five outings and held in-form Manchester United to a goalless draw on Sunday.
Pochettino wants Spurs to take the belief from their recent form into Thursday's London derby and kick 2015 off with what would be an impressive victory.
"We need to believe like [we did against Manchester United] and try to play our game, we need to keep this feeling and try show the same performance," he told the club's official website.
"I think we are in the process that we start to believe more, this is important and [Sunday] was a good example of that belief.
"Every game is different and we need to believe. It's a tough game against first in the table but why not?"
