One of the standout features of Thomas Tuchel's Chelsea is the team's ability to keep a clean sheet.
They don't always come easy, but the qualities of the likes of Kepa Arrizabalaga, Edouard Mendy, Thiago Silva, Antonio Rudiger and more can be relied upon to intervene at crucial moments.
Chelsea have racked up 37 clean sheets with Mendy and Kepa between the sticks, across 69 appearances under Tuchel. As a result, it perhaps still comes as a surprise that the Blues entered the season with Silva, Rudiger, Cesar Azpilicueta and Andreas Christensen all set to see their contracts end at the end of the term.
Silva saw his deal extended in January, but as it stands the other three players are set to leave Stamford Bridge.
The group put in a valiant display if not their most impressive against Al-Hilal, as the Asian Champions League victors put a great deal of pressure on Kepa's goal.
The Spaniard produced some mightily impressive saves to keep Chelsea's lead secure but another moment lingers in the memory.
It was not action that stands out but one so familiar that it feels nostalgic even as it happens. Rudiger produced a stern tackle followed by a forceful scream.
It's a small detail but symbolic of the characteristics the German international brings to the team, alongside his defensive qualities.
Rudiger is unafraid to bring a firm, and usually firm challenge. He produced a game-saving tackle against Zenit, set Chelsea's attitude against Villarreal when he left Yeremi Pino on the floor by the Chelsea box in the UEFA Super Cup Final, and helped earn a Champions League win with his crucial tackle on Phil Foden in the Champions League final.
"It's not just my challenge," said Rudiger of the latter. "It's Azpi's challenge, Christensen's challenge, Reece's challenge, Kai's goal, Mount's assist. It [winning the Champions League] was a good team effort."
There's no doubting the efforts and contributions of that Chelsea team, but Rudiger has a unique ability to set that tone in each and every match.
Few central defenders are encouraged to run forward with the ball and to launch rockets from distance, but tens of thousands of supporters at Stamford Bridge call his name in encouragement.
Allowing Rudiger to reach the final year of his deal is understandable. The turnaround in his contribution since the arrival of Tuchel has been outstanding, and the hierarchy will have questioned the former Roma star's ability to shine outside of the German's system given Rudiger's advancing years.
Reports suggest the Blues have moved closer to their player's £200,000 per week demands with PSG and Real Madrid retaining an interest in his services.
Nevertheless, Rudiger's mind has been firmly focused on Chelsea this season.
The 28-year-old said: "Yes, I find it easy to do. I'm not just saying words, I'm fully committed to the cause. I think I've always shown that.
"There were worse times than this so that's why for me I've found it easy to deal with. I'm focused on what is happening here and on the pitch.
"I owe it to everyone here around the club, the coach, my team-mates and my family so that's why I'm only focused about the important things.
"The other things are speculation - I cannot say anything about that."
With Rudiger at his peak, and possibly heading to the final big deal of his career, it's easy to see how negotiations can be drawn out with each party home to their own hopes and worries.
The Blues have already been linked to new central defenders, most notably Jules Kounde. The Frenchman is unlikely seen as a direct replacement for Rudiger given the longstanding interest but shows the calibre Chelsea want to bring to their backline.
In truth, the Blues probably have the finance and inclination to bring in defenders that could match a number of the German's qualities.
However, his unique charisma is irreplaceable. Alongside the cool, calm and collected Silva, Rudiger brings the fire and application to inspire his teammates.
His commitment to the team in uncertain circumstances has been admirable, while Tuchel has rarely taken the risk to rest Rudiger from his role on the left of the back three.
His future is not yet resolved, and signing Kounde will not prove the solution if the Blues see three contracts expire.
It is easy to see why Chelsea are persisting in their negotiations.
