12 months ago, praising anything to do with Chelsea's defence was nearly impossible.
Under Frank Lampard, the Blues were laughably poor at the back. It didn't matter which two centre-backs played, they were all objectively awful. They matched unwanted club records and were constantly in the highlight reels for all the wrong reasons.
Then Thomas Tuchel arrived.
Almost immediately, Chelsea were sorted. As a team, the Blues have looked incredibly impressive, but the biggest change has come on an individual level.
Andreas Christensen is playing like a man possessed, but one of the most notable transformations has been to Antonio Rudiger, who finally looks like the elite centre-back Chelsea thought they were signing from Roma in 2017.
Frozen out under Lampard, Rudiger waltzed back into the squad under Tuchel and immediately showed why he's so highly rated. His reading of the game has been excellent and his ability with the ball at his feet is an integral part of how Tuchel sets his side up.
Chelsea would not be able to do what they are doing without Rudiger, so it should come as no surprise that the Blues have opened talks with the German over a new contract.
While there are some holes which need fixing in the transfer market, securing Rudiger's future is of the utmost importance to Chelsea. He is about to enter the final 12 months of his deal and was prepared to let that run down not too long ago.
90min understands that Bayern Munich and Paris Saint-Germain are keeping a close eye on Rudiger, and they would fancy their chances of signing him if he does enter the last year of his deal. For a player as important as Rudiger is, that cannot be allowed to happen.
Almost every Chelsea move on the pitch starts from Rudiger. You'll see his short passes allowing Jorginho to spring into life, you'll see him flying down the left as an auxiliary left-winger and you'll also see his long passes set up chances like Christian Pulisic's excellent opener against Real Madrid in the Champions League.
For a team so deprived of creativity in attack, Chelsea need players like Rudiger at the back. He's one of the few players who actually wants to make something happen for the Blues. He deserves a new contract solely based on that.
It's sometimes easy to forget that Rudiger is actually a defender. He spends so much time moving forwards, but that doesn't mean he neglects his defensive duties.
Rudiger has neutralised the likes of Harry Kane, Mohamed Salah and Luis Suarez in his spell back in the team, and the only person to score against him in Tuchel's first five league games was Rudiger himself.
He's brought a calming influence to a Chelsea side who spent 18 months lacking any form of composure. Sure, Tuchel deserves plenty of credit for that too, but he selects Rudiger every week because the defender does half of the work for him.
Chelsea are a far better team with Rudiger in the side than without (you'll notice he missed the 5-2 loss to West Brom), so tying him down to a new contract should be the easiest decision in the world.