With the start of the 2021-22 Champions League, Chelsea and coach Thomas Tuchel will be looking to retain their Champions League title this season.The Blues will have their eyes set on their third European title, and given the squad they currently have, they can indeed achieve it.Our defence of the #UCL starts here!Let’s go! ✊ pic.twitter.com/czDnWOI8Ij— Chelsea FC (@ChelseaFC) September 14, 2021Chelsea undoubtedly have one of the most balanced squads in the whole of Europe. The team is packed with star players all over the field.In the four games that the Blues have played in the Premier League this season, they have gathered 10 points and are currently sitting in second place in the league.Here are three reasons why Chelsea can retain the Champions League title:3 Reasons why Chelsea can retain Champion League titleSolid defensive structureDefense is the basis of success for any team. A good attacker wins you games while a solid defense wins you the title.Ever since Tuchel came in charge, he has transformed Chelsea into a defensive machine. The team's solid defense is their main strength.Tuchel follows a 3-4-2-1 system which is a very versatile formation. The wingbacks play a crucial role in such a formation and provide both defensive and attacking options.The wingbacks get in deep at the time of defending and make it extremely hard for the opposition’s attackers to break through.Chelsea’s defensive stats in the Premier League since Tuchel arrived…Goals conceded (14) - 1st 🥇 Clean sheets (13) - 1st 🥇Shots on target faced (58) - 1st 🥇xG against (15.5) - 1st 🥇 pic.twitter.com/S4TqTZPXOc— LDN (@LDNFootbalI) September 13, 2021The defense is supported by a strong midfield duo of Kante and Jorginho. While both superstars had been instrumental for Chelsea’s success last season, they have quite a different skillset.Kante is much more of a defensive midfielder who helps the team win back possession while Jorginho helps control the tempo and speed of the game.On top of all this, Chelsea have got an absolute beast in the net. Edouard Mendy has conceded just one goal in the four Premier League games that he has played this season.Elite coachThomas Tuchel, who joined the Blues back in January 2021, has completely transformed the club. There was a lot of criticism regarding Tuchel at the start with people doubting him to be capable enough to be in charge of a big club like Chelsea.But after seeing what he has achieved in only his first season at the club, he has become a fan favorite. Tuchel made a statement at the time of his arrival that he would make a team that nobody wants to play and he has done exactly that.Thomas Tuchel on being a Champions League winning coach:“When I started coaching at Academy level, I never dreamed of being at the professional level. It simply wasn’t possible because when I started coaching, it was only ex-players coaching in Bundesliga. Now here we are.” 💯 pic.twitter.com/PwdDSh2CX1— Kai Xtra 🏁 (@Appiahmakkavel1) September 14, 2021Tuchel's superb usage of his players and his strategic gameplay is what differentiates him from other managers. A small display of his tactical supremacy could be seen in the Champions League final against City.The Tuchel era has started and the Chelsea coach has his eyes set on the 2021-22 Champions League.Romelu Lukaku’s additionRomelu’s addition to the Chelsea squad is like adding a cherry on top of a cake. The Belgian striker, who was second in the race to be Serie A's top scorer last season, has started to take the Premier League by storm.🗣"He is our number nine and we are lucky and very happy we are able to share this experience with him."Thomas Tuchel speaks highly of Romelu Lukaku pic.twitter.com/kGBxNgJh7J— Football Daily (@footballdaily) September 13, 2021In the three appearances that he has made for Chelsea since his return to the club, he has already scored three goals and is currently third on the top-scorer list.Strong physical attributes, good aerial abilities and great finishing; Lukaku has got all that it takes to be a top-notch striker.Apart from all this, Chelsea have surreal depth in their squad. This depth not only provides the coach with more options but also helps them attack on all fronts.Chelsea fans will surely hope the 2021-22 season will be another magical year in the club's history as the Stamford Bridge outfit continues to maintain its dominance in Europe.