Chelsea have been rocked by the departures of Antonio Rudiger and Andreas Christensen this summer — but Thomas Tuchel can smile again after landing Kalidou Koulibaly. 

The Senegal international is a high-quality addition to the Blues' depleted defensive ranks, with club captain Cesar Azpilicueta potentially also on his way out of Stamford Bridge. 

Koulibaly has long been coveted by Europe's elite and has finally moved on from Napoli after the Partenopei were forced to sell when his contract entered its final year. 

As Chelsea continue their pre-season preparations in the USA, we take a look at what their newest recruit will offer the West Londoners.

Dominant defending

Koulibaly's reputation as one of Europe's premier defenders is in no way unwarranted. 

The centre-back is a dominant presence — combining his size, speed and tackling technique with an ability to position himself perfectly to snuff out opposition attacks. 

Only three players made more interceptions inside their own penalty area than Koulibaly's 10 in Serie A last term, demonstrating his knack for timely interventions. 

Additionally, he won possession back 101 times in his own third and completed 84 clearances as he led Napoli to the joint-best defensive record in the league — conceding just 31 times. 

Only title-chasing pair Manchester City and Liverpool conceded fewer goals than Chelsea's 33 in the Premier League last season and the Blues will hope their new recruit can help close that gap.

Forward-thinking

Koulibaly is not simply a no-nonsense defender, however. 

The 31-year-old uses his technical quality to aid his side's build-up play — demonstrated by the 1,641 Serie A passes he attempted in 2021-22, completing 1,426. 

These are not merely sideways and backwards either, with the Saint-Die native always looking to progress the ball forwards. 

Only Sassuolo's Gian Marco Ferrari completed more passes into the opposition half than Koulibaly's 260 last term, having attempted a total of 338.

Set-piece threat

Koulibaly's towering frame is not just useful from a defensive standpoint. 

The centre-half is a sizeable target to aim for in the opposition area from corners or free-kicks. 

Each of his three league goals last term came from a set-piece, having outperformed his 1.27 set-piece expected goals in the competition. 

Chelsea fans will certainly hope Koulibaly can chip in with a few strikes in 2022-23.

Deceptively agile

As a central defender, Koulibaly will certainly not be expected to match the dribbling statistics of the Premier League's top wide forwards. 

However, he relishes the challenge of beating his man as he carries the ball out from the back — and the 62-cap international is excellent at doing so when the need arises. 

He only attempted 22 take-ons in Serie A last season but completed 20 of them for a 90.9% success rate. 

Strikers looking to press Koulibaly and pick his pocket next season may find that task more difficult than initially anticipated.

Longevity

A potential elephant in the room is the length of the contract handed to Koulibaly despite his age. 

The four-year deal is a significant departure from Chelsea's previous strategy of only offering short-term contracts to players over 30. 

However, Tuchel is convinced that the Africa Cup of Nations winner can emulate Thiago Silva — another veteran Blues centre-back — and perform at a high level for several more years. 

He said: "[Koulibaly] brings experience, top defending quality, height, and everything we're looking for to play a back three or four. 

"It's another brilliant signing for us and we hope he can show his quality as soon as possible. 

"It's nice that he takes this challenge right now. And we have Thiago Silva, who is even older and super-experienced and still at the peak of his game. We hope Koulibaly can do the same and play for many years for us. 

"He is totally fit and ready for the challenge and he needs to be because we need him in top shape.

"That's what we believe and that's what he is here for."