#4 Key injuries
Both teams will be missing key players because of injuries and that adds another blow to the fixture. Koke and Yannick Carrasco both haven't played for quite a while now. They are back in training, but might not feature in the match. And even if they do, a month-long absence will surely leave a mark on their performance.
In defense, Simeone can't count on Filipe Luis, who's had a number of injury problems this season. The latest one being a pulled hamstring he picked up in the 1-1 home draw with Qarabag.
Real could still be without goalkeeper Keylor Navas, who hasn't played since October 17, and will be missing key offensive personnel. Isco, who's been the spark plug for the side after breaking into the starting XI, returned from international duty with a leg problem. He hasn't yet been completely ruled out, but there's a chance that he could miss the crunch game.
Meanwhile, Gareth Bale is certain to miss the match. He suffered a thigh strain last week in training and will probably be out until 2018. He's missed 40 of the last 60 games for Real through various injuries and it's been counted that overall the Welsh superstar has had 19 different injuries since moving to Madrid in 2013. Talk about bad luck.
You always want to see the best players on the pitch when two great teams meet, but that sadly won't happen in the Madrid derby this time.