They have faced each other several times over the last few years. In the four champions League ties they have played against each other since 2005, both clubs have won two.
Chelsea is coming back at the level they have so consistently operated at over the last decade or so. They know that the Champions League is now their priority.
Barcelona play the game with a fluidity that everyone enjoys. It will be a very interesting game with a physically strong team like Chelsea against a team of the quality and pace Barcelona.
It seems that Barcelona are favourites because they have an abundance of quality, and a player in Lionel Messi who can make the difference against anyone at any time. So, logically, everyone bets more on Barcelona.
But Chelsea are doing well at the moment. They have regained their confidence, and they can have such a hunger and will to win in their squad that they could make things difficult for Barcelona. They have a collection of several high-calibre players.
Fernando Torres is beginning to reach his real level once more and Barca will be well aware of the threat Didier Drogba poses. So I think it will also be a tough game for Barcelona.
Obviously, it's a semi-final with two teams that know each other very well and that faced each other a lot of times. I think it will be fascinating to watch, especially because there is no questioning that Barcelona will try to win the first leg at Stamford Bridge.
Read more analysis from Rafael Benitez on his official website: http://www.rafabenitez.com/