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Their one and only season under Maurizio Sarri seemed to have more downs than ups, yet they finished third and won a trophy.
They started the campaign so well under the Italian, looking like serious rivals to Man City and Liverpool as they went unbeaten in the league until November 24, where they lost to big rivals Tottenham.
A mid-season blip saw Sarri's reign questioned, especially once THAT fallout between Sarri and goalkeeper Kepa Arrizabalaga happened in the Carabao Cup final (watch it again here), in which they lost on penalties.
In the latter stages of the campaign, no one seemed to want to finish in the top four, with Chelsea, Arsenal, Tottenham and Man United all dropping points. But just one loss in their last eight helped Sarri's men secure Champions League football for next season and to even beat Spurs to third.
Had they missed out, qualification for Europe's top competition would have been guaranteed anyway, as they won the Europa League a couple of weeks later, beating Arsenal 4-1 in the Europa League final in Baku, Azerbaijan.
Olivier Giroud, Pedro and an Eden Hazard brace helped them to a comfortable victory in the end, which was Hazard's last act in a Chelsea shirt as well as Sarri's final game in charge.
Is Frank Lampard the man to lead them? The dream scenario for the club is for their legendary former midfielder to succeed as boss but, as it stands, on paper they have appointed a Sky Bet Championship manager who failed to win promotion last term. It is a big step up for him and he is under no illusions how big a job it is, but he showed last season how he can get the best out of young, talented players while placing trust in the more experienced members of his squad. Lampard's experience in the Premier League and Champions League should help and his unbeaten pre-season (at the time of writing) has given them reasons to be optimistic. Managing the club, expectations and everything else is a whole new thing though.
The other question is how will they cope with the current transfer ban hanging over them? Mateo Kovacic was able to complete a permanent move to the club from Real Madrid while Christian Pulisic - as much as he does not want to be compared - has big shoes to fill in replacing Hazard after signing in January before returning on loan to Dortmund. Their squad was in need of a revamp and the ban means a lot of young players could get a chance to impress at Stamford Bridge, so it will be intriguing to see if the likes of Tammy Abraham - their new number nine - Mason Mount and Fikayo Tomori can step up.
The French midfielder may be a doubt to be fit for the new season with a knee injury, but when he returns he will be key to their success.
One of Sarri's downfalls at the club was his insistence on playing Jorginho in the holding role and having Kante further forward and attacking more than he did in his title-winning seasons with Chelsea (2016/17) and Leicester (2015/16).
Lampard must find how to get the best out of both Kante and Jorginho in the middle, but the former is the heartbeat of the team when on song. His engine, work ethic, reading of the game and simplicity is the bread and butter of his game and his style of play in the holding role have drawn comparisons to Chelsea hero Claude Makelele.
It is slightly harsh on Kante when so much of his game is unique in the modern game. It has often been said that when Kante is on the field it is like there is three of him at any given time due to the amount of ground he covers.
Hazard was obviously the main man in previous seasons, but Kante has shown how vital he is, helping both Leicester and Chelsea to the title in back-to-back campaigns.
In 142 Premier League appearances, Kante has impressively made 489 tackles, 367 interceptions and 1,151 recoveries. The most interesting statistic available on him though, is the amount of errors he has made leading to a goal - zero. Amazingly.
If Lampard can get the best out of him, he won't go far wrong during his Stamford Bridge reign.
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Ins: Mateo Kovacic (Real Madrid, undisclosed)
Outs: Eden Hazard (Real Madrid, £130m), David Luiz (Arsenal £8m), Danny Drinkwater (Burnley) Ethan Ampadu (RB Leipzig, loan), Jake Clarke-Salter (Birmingham, loan), Tomas Kalas (Bristol City, undisclosed), Fankaty Dabo (Coventry, free), Rob Green (retired), Brad Collins (Barnsley, undisclosed), Ola Aina (Torino, undisclosed), Nathan Baxter (Ross County, loan), Richard Nartey (Burton, loan), Jay Dasilva (Bristol City, undisclosed), Eduardo (SC Braga, free), Marcin Bulka (Paris St Germain, free), Luke McCormick (Shrewsbury, loan), Matt Miazga (Reading, loan), Lewis Baker (Fortuna Dusseldorf, loan), Gary Cahill, Kyle Scott, Todd Kane (all released)
1. Kepa Arrizabalaga, 2. Antonio Rüdiger, 3. Marcos Alonso, 4. Andreas Christensen, 5. Jorginho, 7. N'Golo Kante, 8. Ross Barkley, 9. Tammy Abraham, 11. Pedro, 12. Ruben Loftus-Cheek, 13. Willy Caballero, 14. Tiemoue Bakayoko, 15. Kurt Zouma, 16. Kenedy, 17. Mateo Kovacic, 18. Olivier Giroud, 19. Mason Mount, 20. Callum Hudson-Odoi, 21. Davide Zappacosta, 22. Willian, 23. Michy Batshuayi, 24. Christian Pulisic, 28. Cesar Azpilicueta, 33. Emerson Palmieri, 52. Jason Cumming, TBC: Marco van Ginkel
The 41-year-old completed his fairytale return to west London ahead of just his second season in senior management.
You have got to credit him for making the brave move. While an offer to manage Chelsea may not come across too often, it is a big risk to his reputation making that step up at an early stage to a club under transfer embargo with a squad in need of a revamp, but he knows the club inside out.
To his credit, in pre-season at least, he has freshened up the squad by introducing some youngsters who had impressive loan spells last season and will be looking for a positive reaction from them in the process.
Last season it took a while for Sarri to get his methods across, especially considering he came late in pre-season, and fans started to get inpatient. Luckily for Lampard, being a fan hero and under the circumstances, it will probably buy him a little bit more time.