Thomas Tuchel hopes Antonio Rudiger's Chelsea future will be resolved soon, and believes the Germany international is "up for the toughest challenge."
Rudiger was signed from Roma in 2017, though despite steadily establishing himself as a consistent Premier League performer, looked to be heading for the exit door when he fell out of favour with Frank Lampard in 2020.
A move did not materialise and Rudiger came back into the fold under Lampard before the Chelsea legend was dismissed in January.
Since then, Rudiger has gone from strength to strength under his compatriot Tuchel, playing a key role as the Blues went on to win the Champions League last season.
Yet his future at Stamford Bridge is unclear. The 28-year-old's deal runs out at the end of this season, meaning he will be free to hold talks with clubs from overseas come January 1 – Paris Saint-Germain, Real Madrid and Bayern Munich have all been linked with the centre-back.
Talks over a new deal are ongoing, though Tuchel warned it is not an easy process.
"It is pretty clear what we want but it is not like this in football that the coach or the club wants something but other things happen," Tuchel said during a news conference ahead of Chelsea's trip to Leicester City on Saturday.
"You have to accept it. Sometimes you can end up in situations where things are at a bit of a delay and things maybe take their time."
Tuchel also thinks Rudiger wants to keep testing himself at the highest level, however, and the former PSG coach believes that means staying in the Premier League.
"I am very sure also that Tony feels respected and knows what an important role he plays in this club," he added.
"I think he's up for the toughest challenge. The toughest challenge is to play Premier League football, to win titles.
"He is a big part of a big club and I am sure that he is aware of it. I am calm, I feel Tony is calm, I feel the situation inside here is calm. From here we go. I am happy that he plays how he plays. We need him on this kind of level."
Rudiger's vital role at Chelsea
So, just how important is Rudiger to Tuchel's system? Firstly, his versatility is a real asset. Capable of playing anywhere across the three-man defence in Tuchel's preferred formation, the former Stuttgart man, who was also deployed as a full-back during his time at Roma, has pace to burn, making him an ideal partner for the slower Thiago Silva, or even Andreas Christensen.
His pace also allows him to cover the left side of defence, where he is most often utilised, enabling Chelsea's left wing-back – either Marcos Alonso or Ben Chilwell, who last month became the first English player to score in four consecutive Premier League games for Chelsea since Frank Lampard in February 2013 – to drive forward.
Since Tuchel's first game in charge on January 27, Chelsea have kept 29 clean sheets in all competitions, eight more than any other team across Europe's top five leagues. Rudiger has featured in 24 of those matches, helping to keep more shut-outs than any other player in Chelsea's squad.
Fifteen of the clean sheets Rudiger has helped to keep have come in the Premier League, with no other player in the competition managing more. Indeed, the only player level in that regard is his club-mate Edouard Mendy, who has been brilliant in goal.
Only Manchester City star Ruben Dias (19) has contributed to more victories than Rudiger (16), whose duel success rate of 61.59 is second only to Silva in Chelsea's pool of defenders. His aerial presence is a threat in both boxes, and he has won 50 out of 70 aerial duels.
He also acts as a ball carrier in Tuchel's team, with only Mateo Kovacic (480) carrying it forward on more occasions, or further than Rudiger's 4,302.8 metres. A carry is defined by Opta as a player travelling with the ball for at least five metres.
Rudiger has missed just eight games in all competitions since Tuchel took over, playing 40 times. The impact on Chelsea's defence is notable. When Rudiger features, Chelsea's average goals against stands at 0.4, compared to 1.0 when he is not in the side.
The Blues win percentage also drops from 65 per cent down to 50 per cent, while their points per game also takes a hit, going from 2.2 to 1.8.