Tottenham beat the Blues 2-0 at White Hart Lane in January, while Chelsea won the reverse fixture 2-1 at Stamford Bridge last November, making the semi-final difficult to call.
And Chelsea midfielder Matic feels they have been the most difficult opponents of the campaign.
"They are very good, for me maybe the strongest in the Premier League from the opponents we have faced this season," he told the club's website.
"They are hard to play against because they are strong physically and they can also play with the ball. So we must be ready for that, to stop them and to play our game.
"Every game is different but we know they are going to be aggressive. They have many good players and we have to be ready for that. We have trained well this week and I am sure we will be."
Matic thinks the victors at Wembley could hold a mental advantage in the Premier League title race, with Chelsea just four points clear of Spurs going into the final six matches.
"Maybe [the winners could land a psychological blow] - we will see about that," he said.
"After the semi-final we have to focus on the Premier League. We have six games left and five we have to win if we want to be champions. That is all we players will think about, whatever happens at Wembley.
"But really we want to be in the final and we will try to do everything to be there.
"Most of this team have not won the FA Cup and we would like to win it. We also know it is something special for the people. We are confident we can do it."
Chelsea come into the game on the back of a disappointing 2-0 defeat away to Manchester United, which saw Antonio Conte's side fail to register a shot on target.
Matic said: "We have already forgotten last Sunday's game. That is important because a new game brings new challenges and that is what we have to focus on. It is the same when we win.
"We know we will have to play better than last weekend and I think we will. I am feeling good and the atmosphere at Cobham has been good. We are ready."