I don't think Chelsea have a lot of chances against Real Madrid, even if they play well in defense and there is a draw in London, Real will not miss the opportunity to beat Chelsea in Madrid.
They just luckily won over Dortmund and went to quarter finals. They are worse than in the past season when they mostly won big against Real Madrid in a second leg match but Real Madrid with their champion mentality pulled the match back and did not allow Chelsea to make a big shock.
In this season both clubs have decreasing performances but more severity is seen in Chelsea than in Real Madrid that makes Real Madrid again is a likely a winner.
Chelsea have a small chance if they play well in defence, which they do well, and will be able to take chances in the counter attack, but I think that these chances will be few and everyone will need to be treated very carefully.
It's reasonable for a weaker team play defensive against a stronger team but unfortunately Chelsea defense is not actually good in this season. I don't think they will be able to keep their goal clean after two matches against Real Madrid. With poor performance from their attacking players, it's super hard for them to score goals when Real Madrid have Courtois.
It's hard to say if chelsea will able to copy barcelona and implement the same strategy as barcelona. It's caused by chelsea not having some capable defenders to do that. you can't even see chelsea's defenders are on the same level as barcelona. Chelsea defenders are very often made so many blunders.
The strategy used by barcelona is to use counter attack against real madrid.
They can try to copy Barcelona approach but gaining same result like Barcelona is difficult. Barcelona have very good defense in La Liga and in attacking system, they have many good players who are playing well in this season. Barcelona are in much better form than Chelsea and they won Real Madrid does not lead to a similar win for Chelsea.
Especially from now, Real Madrid will totally focus on Champions League and they will use all resources to beat Chelsea.
We don't need to use domestic league to give statistics of the outcome of the game. Barca is not Chelsea,perhaps Barca is in a good form and very strong this season which we saw that in their performance but Chelsea is still struggling to pick form and nobody knows if they are deform currently. Real Madrid no matter their difficulties to win Barca doesn't mean that they will not take the UCL game serious. They have being performing better in UCL matches than Laliga matches. For this reason I don't think Real Madrid will lose to Chelsea who is weak this season. Real Madrid is the favourite to be in this match home and away.