Chelsea manager Antonio Conte has enjoyed a "position of privilege" by not having to deal with both European and domestic campaigns in his first season in England, Manchester United boss Jose Mourinho has said.
Chelsea sacked Mourinho 16 games into a dismal campaign last season, which saw them finish 10th in the Premier League and fail to qualify for even the Europa League.
Conte, who joined the London club at the start of the season, has led the club 10 points clear at the top of the league but Mourinho suggested a lack of European commitment had aided their title charge.
"The most difficult thing to have is time to work, and they have time to work," the Portuguese told British media ahead of Monday's FA Cup quarter-final clash at Chelsea.
"They are in a position of privilege -- the same privilege that Liverpool had a couple of years ago and they almost won the Premier League -- but I don't want to say that they don't deserve credit for it.
"They choose a certain style of play that I think is very adapted to the qualities of these players.
Mourinho, who lost 4-0 on his return to Stamford Bridge with United last October, said that playing his former club did not provide any extra motivation.
"Am I sadder to lose against Chelsea than against another team? No. Am I happier to win against Chelsea than another team? No," the 54-year-old added.
"I am focused on Man United and I know the work I did there, I know what I did but I am the kind of guy that I move and have no regrets and I am not looking for bad feelings at all."
United were held to a first leg 1-1 draw in the last-16 Europa League clash at Rostov last week but Mourinho said he would not field a weakened team against Chelsea.
The Old Trafford club host the Russian outfit in the second leg on Thursday before travelling to Middlesbrough in the league on Sunday, to complete a run of three games in seven days.