Manchester United manager Jose Mourinho is "surprised" by Chelsea's style of play under Antonio Conte.
Mourinho makes his latest return to Stamford Bridge in Monday's keenly anticipated sixth-round clash, having suffered a chastening 4-0 Premier League loss against his former employers back in October.
During his two title-winning spells in charge of Chelsea, the Portuguese was often criticised for an overly pragmatic approach but, in an interview with BBC Football Focus, he repeated an assertion made last month that Conte's runaway league leaders are a defensive team
"No, I am not surprised [by Chelsea's success this season], I am surprised with the way they play," said Mourinho, whose United have scored 39 top-flight goals this season compared to Chelsea's 57.
"I am surprised because I thought they were demanding a different kind of football.
"I think Chelsea are phenomenal, but Chelsea are an amazing defensive team."
Pedro's goal after 30 seconds set up a damaging outing in London last time around for Mourinho, but he insists he is not motivated by the prospect of retribution as United seek to retain the trophy they won under Louis van Gaal last season.
"I'm not looking for revenge, I'm not looking for anything wrong or bad," he explained.
"It is maybe something special to have Gary Staker [Chelsea's player liaison officer] in the tunnel before and after the match - a close, super friend.
"So if it is different, it is different in a positive way; it is not different in a negative way.
"I think they are very good defensively and have excellent players to be a counter-attacking team and kill teams with three or four players."