The 2021-22 UEFA Champions League is back and a must-watch game is upon usPSG make the trip to Spain to take on Real Madrid in the second leg of the round of 16, but Sergio Ramos is once again ruled out for the game.

Paris Saint-Germain got the upper hand in the first leg played at the Parc des Princes thanks to a Kylian Mbappe last-minute winner. Carlo Ancelotti's side heads back home aiming to turn things around after a dreadful performance in Paris. 

Mauricio Pochettino, meanwhile, knows he has to deliver results in these kinds of games so it will be a great opportunity for his team to take another step towards the coveted trophy. It's not a secret that PSG's hierarchy only wants one thing for this season and that is to become European champions for the first time. That explains their stellar signings in the summer transfer window, but not all of them went as expected - especially Ramos.

Here's why Sergio Ramos is not playing for PSG vs. Real Madrid

When Paris Saint-Germain landed Ramos in a free transfer last year, it looked like they were preparing to go all in for the Champions League title. However, the months have passed and the defender has failed to make at least one UCL appearance in a PSG uniform.

He was expected to make his debut against Real Madrid, but he didn't make it in time for the first leg. Sergio Ramos is not playing for PSG in the second leg of the Champions League round of 16 either because he hasn't recovered from a calf injury.

"Sergio Ramos is training on his own until the end of the week and will travel with the squad to Madrid," a PSG statement read. The 35-year-old center-back has spent most of the time on the sidelines this season, playing just five games for PSG so far.