The highly-anticipated second leg of the UEFA Champions League last-16 clash between Real Madrid and Paris Saint-Germain is only five days away, and Los Blancos have been dealt with a major injury blow. It has been revealed that midfielder Toni Kroos is dealing with a muscular issue.

News outlets were quick to notice that the German ace was missing from training on Thursday. According to Marca, he is set to undergo tests but the prognosis is not looking good. In fact, he may not even be available to feature in Real Madrid's La Liga fixture on Saturday evening against Real Sociedad.

Manager Carlo Ancelotti is being kept abreast of the situation, and he will have to make some tough decisions if the problem persists into midweek. Paris Saint-Germain will visit the Santiago Bernabeu on Wednesday bearing a 1-0 advantage from the first leg. As such, Ancelotti will want all of his best players available to help mount a comeback in the second leg in front of home fans.

Kross has been an integral part of Real Madrid's prolific midfield trio alongside Luka Modric and Casemiro. That means that Ancelotti is now facing a much bigger problem, owing to the fact that Casemiro will also miss the second leg due to suspension.

Fede Valverde was initially believed to be the man that Ancelotti was counting on to fill in for Casemiro, but with Kroos also unavailable, he will have to find a different formula. Eduardo Camavinga may finally have an opportunity to shine, if he is given a staring position.

Kroos, like striker Karim Benzema, has been a key figure for Real Madrid for the past several years. He has hardly ever been left out of the starting lineup except out of necessity due to injury. He underwent treatment for a groin injury in the off-season, and started the campaign a few weeks late. He has since missed only one game and has made 29 appearances in all competitions for Real Madrid this season.

Toni Kroos
Real Madrid midfielder Toni Kroos has been key to the club's success AFP / JORGE GUERRER