The one big problem with Roma in the Champions League is when they lose, it's generally by a hatful.
Over the last few seasons, the Italians have conceded sixes and sevens on occasion, far too much for a team of such quality.
However it seems by going a goal or two down, heads drop and the game is lost from that point onwards.
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That certainly appears to be part of the reason why Rudi Garcia was given the elbow and replaced by Luciano Spalletti.
Expectancy will be high at the Stadio Olimpico that the new man in charge can bring the goods over the course of two legs.
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Zinedine Zidane hasn't been too concerned in the lead up to this game, but perhaps he should be.
Let's take a look at three things that could affect the outcome of this one.
Los Blancos won't need reminding about their poor record when it comes to playing Italian teams in Europe.
Knocked out at the semi final stage to Juventus last season, it's been 28 long years since Real managed to defeat an Italian side in the knockout stages of European competition.
Napoli were the last to succumb to the might of the Spaniards in 1987. Since then however, Real have been knocked out by Torino and Roma once, AC Milan twice, and four times by Juve.
Indeed, they've lost all of their last three encounters against Italian opposition.
Whether there is a mental block for some players, or the catenaccio style doesn't suit the Spanish game is unclear.
What is clear is that Zidane's troops are going to have to alter the weight of history in order to qualify for the next stage. A big first leg win is therefore required.
It's worth pointing out that Roma have only lost once at home all season and that was in the aftermath of the defeat at Camp Nou back in November.
That league loss to Atalanta also happens to be one of only two - the other was against Juventus - that Roma have suffered since the end of the group stages of the competition.
Just 10 goals conceded in their last 13 games speaks of a side that are rock solid defensively and whilst they might not score many themselves, that they don't concede gives them every chance of taking the points in each game they play.
The hosts have also won their last four games and Spalletti will have them right up for this challenge.
Cristiano Ronaldo appears stung by recent criticism that he is only scoring against the supposed "weaker" sides, with respect, in both La Liga and the Champions League.
The leading scorer in European competition, this match is the perfect setting for the Portuguese to answer his critics.
How many times have we seen in the past that when the chips are down or Real need something special, Ronaldo pops up and provides it.
This isn't a game for clipping his wings either. Let him have the ball when he wants it and wherever he wants it. The showman needs a stage. This is it.
How far can Real go in this year's Champions League? Have YOUR say in the comment box below!