"I can't believe what I'm seeing."

Few could.

Paris St-Germain have been swatting aside all-comers all season, from wrapping up the Ligue 1 title in early April to demolishing Inter Milan in a Champions League final so one-sided it was scarcely believable.

They seemed to be breezing through the Club World Cup in similar fashion, too, beating Bayern Munich with nine men and then thrashing Real Madrid 4-0 on their way to Sunday's final.

But, heavily tipped to cruise past Chelsea in New Jersey, this time it was the Parisians who were left stunned.

Even before Coldplay's colourful half-time show arrived, Cole Palmer had scored two superb goals and created another for Joao Pedro to put the Blues 3-0 up. That is how it ended.

"I've never seen PSG turn the ball over as much as they have in this first half," said former England midfielder Andros Townsend on Dazn.

"Full credit to Chelsea for their willingness to track the ball in this New York heat."

It was Townsend who said he could not believe the scenes playing out on the MetLife Stadium pitch. There was widespread astonishment.

As fellow pundit Gareth Bale put it: "PSG have been PSG'd."

So how did Enzo Maresca's side manage it? And just how good are Chelsea?

As has often been the case over the past two years, Palmer playing well meant Chelsea played well.

The 23-year-old has operated predominantly down the middle as a conventional number 10 for much of this season, but at times he struggled in that position. At one point he went 18 games without scoring and recently admitted he had endured a "difficult time these past whatever months on and off the pitch".

However, having been moved back out to the right during this tournament - a position he made his own under previous boss Mauricio Pochettino - he has looked somewhere near his best again.

Chelsea had clearly prioritised a fast start in the final, with Maresca saying he thought they "won the game in the first 10 minutes", with their aggressive approach and high press putting their opponents under unfamiliar stress.

"The idea was go man-to-man because if you leave spaces to PSG they will kill you, so we tried to be very aggressive and suffocate them early on and that intensity was crucial in the first 10 minutes," Maresca said.

Once Chelsea had asserted their authority, it was then obvious they were keen to target PSG's left-hand side, as Joao Pedro frequently drifted out wide to pair up with Palmer.

Their method was often direct, with passes dropped in behind the PSG defence, but it meant left-back Nuno Mendes was given a torrid time.

"We had a lot of success exploring the left side of their defence," said Maresca. "Things worked perfectly for us due to the effort the players put."

Townsend described it as a "tactical masterclass".

"That's what they've done - they've stretched this PSG defence, we've never seen a team do this to them," added ex-Chelsea midfielder John Mikel Obi.

There has been much debate about how much this newly expanded competition means.

But the trophy does mean you can call yourself world champions - until the next competition is played, scheduled for 2029. And Chelsea will be able to wear a badge on their kit to reiterate it.

It's also been worth between £80m and £90m in prize money.

"The fans will have bragging rights for the next four years," said Townsend.

"Nobody will be able to say anything to Chelsea fans because they are world champions - not for one year but for four years until 2029. Wow, what an achievement."

And there was no doubting how much it meant to the players and staff, who celebrated it as enthusiastically as they would have a Champions League or Premier League trophy.

Their players clashed with PSG's team on the pitch afterwards, with the French champions visibly upset with the defeat - with Blues boss Maresca acting as peacekeeper.

"I feel that this competition will be as important as or even more important than the Champions League," said Maresca.

"I was lucky enough to be part of a coaching staff [at Manchester City] that won the Champions League three years ago, but this competition features the best clubs in the world. That's why we value it as much as the Champions League, or perhaps even more.

"For us, it was a great triumph. Allowing Chelsea fans to wear that world champion patch on their shirts is a source of pride for us."

Palmer added: "It's a great feeling. Even better because everyone doubted us before the game, we knew that. To put a fight on like we did, it's good."

Many have laughed at Chelsea's recruitment under Todd Boehly. They have spent somewhere in the region of £1.5bn on players since his takeover in 2022 - and handed out a host of contracts lasting seven, eight and nine years.

Eighteen months ago Gary Neville called them "billion-pound bottle-jobs" after they lost the Carabao Cup final to Liverpool.

But after the Conference League and Club World Cup trophies this year they are actually looking good. They had the youngest squad of any team at the Club World Cup, with no player older than 27. So they should only get better.

So could they think of challenging for the Premier League title now?

Wales legend Gareth Bale, watching for Dazn, said: "I don't think they're far off at all. Last season before Christmas everyone was talking about them as contenders.

"Obviously they're a young team and fell, but I think they'll learn a lot from that. They've shown a lot of character to come back and win the Conference League and now this. Confidence will be booming - they'll have that self-belief now."

BBC Sport reporter Nizaar Kinsella, who was watching at the MetLife Stadium, said: "Chelsea are firmly behind Maresca and there is a sense of stability about the club for the first time since the UK government placed sanctions on Roman Abramovich after the war in Ukraine started in March 2022.

"This is a new club - but one capable of winning again - and those involved want recognition for their achievements.

"Moises Caicedo and Enzo Fernandez should be considered among the best midfielders in the world. Marc Cucurella is arguably the best left-back in the Premier League and potentially in the world.

"There is promising talent coming through like Levi Colwill, Malo Gusto and newer players like Andrey Santos.

"Joao Pedro has three goals in three Club World Cup matches and was crucial to Chelsea's tournament success, while fellow striker signing Liam Delap has looked lively in the United States.

"Another new signing - Jamie Gittens - has yet to join from Dortmund, with Palmeiras' teenage sensation Estevao Willian also joining for pre-season in August."