Chelsea will pose a threat quite unlike what Real Madrid have faced so far in this edition of the UEFA Champions League.Real Madrid are within reach of yet another UEFA Champions League title but they will have their work cut out for them as they go up against a resilient Chelsea side in the semi-final. Real Madrid squandered the opportunity to pull level with La Liga leaders Atletico Madrid on points as they settled for a goalless draw against Real Betis over the weekend.But they will feel confident about their chances in the Champions League after seeing off Liverpool in the quarter-finals. Chelsea, meanwhile, beat FC Porto 2-1 on aggregate to advance to the semis but Tuchel will be wary of Real Madrid's experience and record in the Champions League semi-finals.The Champions League has been a great hunting ground for Real Madrid and they will be hoping there is no departure from that trend when they lock horns with the Blues this week. But there's every chance that it is going to get really tough for Los Blancos. Without further ado, let's take a look at five reasons why Real Madrid will struggle against Chelsea.#5 Chelsea are a well-rounded, well-balanced sideN'Golo Kante and JorginhoChelsea have been a different team altogether ever since Thomas Tuchel took over as coach. One admirable thing that Tuchel did right away was to get rid of any sort of shakiness. Under his tutelage, there is clarity over what players are expected to do and that has lent itself to making Chelsea a very organized unit.The beauty of this unfolds in Chelsea's transitions. They always have an adequate number of personnel while going forward and while defending. While the wing-backs join the forwards and attacking midfielders in attack, the rest sit deep to nullify the opposition's counter-attacking threat.Chelsea are also at near full strength. Mateo Kovacic is the only one who's sidelined with an injury and they have admirable squad depth. As such, one thing's for certain and it is that there won't be any iffyness about the way Tuchel's team goes about their business in the semi-final.Most clean sheets in Europe’s top 5 leagues:🥇Chelsea: 29🥈Manchester City: 28🥉PSG: 23🥉Manchester United: 2313 for Frank Lampard, 16 for Thomas Tuchel. Credit to them both for improving a defence that was very leaky last season👏🏼 #CFC | #WHUCHE pic.twitter.com/C68JTwX6pU— ChelseaFCBlogs (@ChelseaFCBlogs_) April 24, 2021#4 Chelsea wing-backs will cause Real Madrid problemsManchester City v Chelsea: Emirates FA Cup Semi FinalOne of the major changes that Tuchel made to the system after taking over at Chelsea is switching from full-backs to wing-backs. The Blues have been playing with a three-man defence with wing-backs operating on both sides.The wing-backs' primary duty is to get involved in attack and this helps Chelsea create an overload of sorts down the flanks. What this does is it constantly causes opposition defenders to be pegged back in their own halves.To make matters worse for Real Madrid, Ferland Mendy was sidelined in the game against Real Betis. He is tipped to return to the fray but his fitness could be a cause for concern for Zinedine Zidane. Dani Carvajal returned to the first-team very recently and is not exactly at peak fitness either.As such, the Real Madrid wing-backs will have their hands full all game and cannot afford to be complacent for a second.Will be interesting to see how Reece James copes with Eden Hazard tomorrow, if both are on the pitch at the same time. pic.twitter.com/eTAxC2V01N— Frank Khalid (@FrankKhalidUK) April 26, 2021