Last September was a very different place at Chelsea and almost nothing that has happened since was predicted at the start of the season. But there is one thing that Antonio Conte called at the very start, which has been utterly vindicated. “David Luiz is 29,” Conte predicted when Chelsea re-signed the Brazilian, “a fantastic age for him to become one of the best defenders in the world.”

The words were laughed at back then, with people always seeing the worst in Luiz, especially after he was phased out of Chelsea by Jose Mourinho and then embarrassed by Germany in the World Cup semi-final that summer.

But the reality is that Conte has been proven absolutely right by Luiz this season. He has been the best centre-back in the country by a distance. There have not been many better in other leagues either. Luiz has never had a better claim to be the world’s best than he does right now.

Chelsea are clearly going to win the Premier League title and their players are sure to take the PFA and FWA player of the season awards in May. Diego Costa would surely have won, but his toys did not stay in the pram during a tumultuous January. Eden Hazard says he is playing even better than in 2014-15, when he was footballer of the year. N'golo Kante is due some recognition as he picks up his second consecutive league title.

And yet there is an argument that David Luiz is less replaceable to Chelsea than any of those others. They can win without Costa, and even without Hazard they can put Willian into the front three. Kante’s energy is vital but they still have a solid pair in Nemanja Matic and Cesc Fabregas.

But David Luiz is the lynchpin of the whole 3-4-3 system which is winning Chelsea the title. Playing in the middle of the back three he combines athleticism in defending one on one with the ability to bring the ball out from the back. Conte is not sure about using Luiz in a pair, but in a three he is unmatchable.

On Sunday at Turf Moor Luiz played again with a heavily strapped left knee. Conte called him a “warrior” in his Friday press conference for pushing through the pain barrier. Even though his mobility was impaired, Luiz was still brilliant. Andre Gray is dangerously fast but Luiz never let him escape in behind. The one chance Luiz offered up was when he was slow to turn and intercept Ashley Barnes, understandable in the circumstances.

Burnley vs Chelsea player ratings Show all 22 1 /22 Burnley vs Chelsea player ratings Burnley vs Chelsea player ratings Tom Heaton – 5 out of 10 Chelsea had two shots on target in the first seven minutes and that’s it. So, it was a relatively quiet day for the keeper. Burnley vs Chelsea player ratings Matthew Lowton – 5 out of 10 Made a number of late challenges, but aside from that he held his shape well and used possession well. Burnley vs Chelsea player ratings Michael Keane – 8 out of 10 Was a rock at the back for Burnley today – made countless interceptions, tackles and clearances. Burnley vs Chelsea player ratings Ben Mee – 6 out of 10 His defensive lapse gave Costa the chance to take the lead, but he escaped. Burnley vs Chelsea player ratings Stephen Ward – 7 out of 10 Read the game very well from the back and cleared danger confidently and calmly. Burnley vs Chelsea player ratings George Boyd – 6 out of 10 Worked as an engine in the middle of the park and gave good service to the forwards. Burnley vs Chelsea player ratings Joey Barton – 6 out of 10 His temper began to flare as the game progressed, but this aside, he worked hard and his through balls were dangerous. Burnley vs Chelsea player ratings Ashley Westwood – 5 out of 10 Made wrong decisions in possession at times, but tracked ball well to support the defence. Burnley vs Chelsea player ratings Robbie Brady – 8 out of 10 His goal was the perfect way to announce himself at Burnley – true example of his limitless ability. Burnley vs Chelsea player ratings Andre Gray – 7 out of 10 He was hunting possession, chasing every loose ball and being an all-round nuisance up top. Getty Burnley vs Chelsea player ratings Ashley Barnes – 6 out of 10 He was confident in possession and he was not afraid take a shot on goal – which is encouraging. Burnley vs Chelsea player ratings Thibaut Courtois – 5 out of 10 Stood no chance of saving Brady’s set piece and following that he only had to make a small number of stops throughout. Burnley vs Chelsea player ratings Cesar Azpilicueta – 5 out of 10 Defensively he was caught out of position from time to time, but looked dangerous going forward. Burnley vs Chelsea player ratings David Luiz – 6 out of 10 He was clearly carrying an injury today, as he limped from the start. Nonetheless, he put in a shift and held his own at the back. Burnley vs Chelsea player ratings Gary Cahill – 6 out of 10 Defended bravely throughout and made a handful of vital stops and clearances. Burnley vs Chelsea player ratings Victor Moses – 7 out of 10 Caused Burnley problems when he charged down the right. He also assisted Pedro’s opener. Burnley vs Chelsea player ratings N’Golo Kante – 6 out of 10 As always, he was a key element to almost every Chelsea move going forward. Also, he done well in terms of his defensive duties. Getty Burnley vs Chelsea player ratings Nemanja Matic – 5 out of 10 His tackling today was clumsy and this gave Burnley a number of unnecessary free kicks. Burnley vs Chelsea player ratings Marcos Alonso – 6 out of 10 He created space very well down the left, but needed to do more with the ball when he received possession. Burnley vs Chelsea player ratings Pedro – 6 out of 10 His goal gave Chelsea the early advantage. He worked relentlessly, but was unable to find a second. Burnley vs Chelsea player ratings Diego Costa – 6 out of 10 Made a number of clever decisions, but he continued to go to ground for little/no reason. Failed to test Heaton. Burnley vs Chelsea player ratings Eden Hazard – 7 out of 10 He was terrific throughout, as he continued to terrorise and entice fouls from the Burnley defence.

Luiz’s use of the ball was as good as ever. He did not score a brilliant free-kick, as he did at Anfield, but his long passing to set up the counter-attack was always good. And when he had to hoik the ball through the gap between the James Hargreaves and David Fishwick stands onto the cricket pitch behind, he could do that too.

He is the type of defender that Manchester City have been desperately looking for this season, the type of player that Pep Guardiola had before <p> </p>

There are not many centre-backs who have that combination of skills, athletic and footballing. That is what Conte meant when he said back in September that Luiz’s qualities are “in the middle” between Leonardo Bonucci and Andrea Barzagli. “Good technique, personality like Bonucci,” Conte said. “Good potential physically like Barzagli.”

That is the type of defender that Manchester City have been desperately looking for this season, the type of player that Pep Guardiola had before in Gerard Pique or Jerome Boateng, who could be trusted to defend one-on-one, freeing most of his team-mates to go and attack.

Luiz has developed into one of the Premier League's best defenders while away from Chelsea (Getty)

If City had signed Luiz then this season might have turned out differently for them, but in the real world they have been scrambling at centre-back all season. They have conceded 29 goals, more than Middlesbrough and Everton, and kept just five clean sheets, fewer than Bournemouth, West Ham United, Stoke City and Burnley.