London - Chelsea manager Jose Mourinho believes the pressure is on Manchester City to lead the way in this season's Premier League title race.
Mourinho thinks that there are six contenders to win the championship, but he has warned Manchester United and Tottenham Hotspur that they could find themselves cut adrift if they allow the gap to leaders Arsenal to grow.
And while the Portuguese insists there are no clear favourites, he feels that the strength of City's squad gives Manuel Pellegrini's side an advantage.
"I keep saying the same. I don't think we can speak about favourites but we can say that one team is top of the league and some are a little bit far, but I keep thinking that all six teams are title contenders," he said on Tuesday.
"But I keep saying that the team with more responsibilities to win it because their squad is quite unique is Manchester City."
Chelsea sit four points behind Arsenal in second place and two points above third-place City ahead of the mid-week round of fixtures, which sees Mourinho's side visit second-bottom Sunderland on Wednesday.
United and Tottenham, however, are well off the pace, trailing Arsenal by nine and 10 points respectively, and Mourinho feels that they are already in danger of slipping out of contention.
"United are nine points behind Arsenal. It's a gap. Nine points is a gap, Tottenham 10. That's a gap. It's not a gap for us," he said.
"For us, we are speaking about four points. That's not a gap. It's something that, in two matches, is over. But nine or 10 points is a gap.
"They know that if the next step is to reduce from 10 to seven, nine to six, it's to go again into the race. But if the next move is from 10 to 13, or nine to 12, it becomes hard.
"In this moment, some teams like Arsenal are a lot more comfortable because they can slide one match and nothing happens to them.
"Some other teams know the next night can be crucial. But the six teams are very equal in their potential."
The former Real Madrid manager, who also includes Liverpool among the title contenders, added: "But I keep saying: there's a lot to play in December. At the beginning of January we can have a look and say if all six are with short distances, or if someone has opened up a real gap.
"At this moment until the end of the year, it's a moment not to decide but to clarify a bit the situation."
Chelsea striker Samuel Eto'o is fit again and could return for the trip to the Stadium of Light, but left-back Ashley Cole has been warned he could miss out again as he battles to reclaim his place from Cesar Azpilicueta.
Mourinho admits that the England international is being forced to come to terms with an unfamiliar role of understudy.
"I think any player that normally starts matches, and Ashley has started matches through all his career, when they don't start, naturally they're not the happiest guy in the camp," he said.
"He deserves to play but Azpilicueta is doing really well, so it's a question of Ashley working and waiting for his opportunity. But he's more than ready to play."
With a trip to Stoke City to follow on Saturday, Mourinho added: "He could play in one of these two matches. I think he will. Or, if I decide not to, next week against Steaua Bucharest (in the Champions League).
"It's a position where Azpilicueta has played a group of consecutive matches, so sooner or later I'll have to change, so Ashley will play soon."