Jose Mourinho believes his Manchester United side will find it tough to reduce the deficit between themselves and league leaders Chelsea because the Blues are unlikely to drop many points until the end of the season.
Mourinho's United team currently sit in sixth place in the top-flight standings - 13 points off the Portuguese's former side Chelsea, who lead the standings by a comfortable six-point lead.
Part of the success of Mourinho's permanent successor, Antonio Conte, has been to instil a defensive solidity to Chelsea's back line, which has coincided with the switch to a 3-4-3 formation in October.
Since the tactical change, Chelsea have conceded just two goals and secured three straight 1-0 wins over West Brom, Sunderland and Crystal Palace.
And Mourinho believes the Blues' ability to avoid letting in goals has made them difficult to catch in the Premier League title race.
"You have to be honest and say that is very difficult," Mourinho told Sky Sports when asked if United could still win the title.
"It's not just the difference in points, it's also the Chelsea philosophy of playing.
"They score one goal and they win. They defend a lot. They defend well. They are winning and, in the last 20 minutes, they bring defenders in.
"They don't care what people say, what people think. They just want to win. And, because of that, I don't see them losing many points."
