Six things noticed from Chelsea's 4-1 defeat to Celtic.

 The Enzo Maresca era is continuing and so far, it looks more and more confusing as to why Chelsea decided to dispense with Mauricio Pochettino.

A draw with Wrexham and now a truly terrible defeat to Celtic will only lead to more questions from fans and rightly so after a strong end to last season.

In the hazy heat of the United States, the Scottish giants were simply so much better than their Premier League opponents.

Just 18 minutes in, Celtic had the lead and one they richly deserved. Matt O'Riley finished smartly in the box after some clever interplay, beating Robert Sanchez, who had made more than one excellent save beforehand.

Before the half-hour mark, Celtic should have been 2-0 up, but Kyogo Furuhashi was denied by Sanchez at close range in superb fashion.

But he made no mistake two minutes later, finishing a cross into the box to hint towards something approaching humiliation for the Blues.

Enzo Maresca made expected changes at half-time and Raheem Sterling, on as a sub, hit the bar within a minute.

But they faded badly, and Celtic scored a third and fourth in quick succession, twice taking advantage of some absolutely dreadful defending, particularly from Benoit Badiashile, in what quickly became a nightmare.

Christopher Nkunku pulled one back from the penalty spot late on but ultimately, humiliation it was.

Here are six things noticed from Chelsea's loss to Celtic:

1. Chelsea's Defense:

Throughout the game, Chelsea were repeatedly cut open by simple, quick passing from Celtic. They started with a back three, with Wesley Fofana, Benoit Badiashile and Levi Colwill, and none of the three played well.

Brendan Rodgers' side seemed to clock the deficiencies in the Blues' system early in the game, and were very quick to move the ball up the pitch, sometimes going from defence to attack with one through ball.

On more than one occassion, Celtic worked an opening in which they produced an overload, and isolated a Chelsea defender, and scored with a similar move, as multiple quick passes around the box opened up space for O'Riley to pass into the back of the net. The second goal was probably more troubling, as Celtic came down the right-hand side, played the ball in behind the backline, and Kyogo finished a simple cross. It was too easy.

Add the third goal - Badiashile merely passing the ball to Luis Palma on the edge of his own box in a truly moronic piece of play - and a fourth in which barely anyone made any moves to stop the Celtic attack and it adds up to a defensive disaster.

Enzo Maresca has accepted that Chelsea will concede goals playing his style of football, but this was truly disastrous.

2. The Cole Palmer influence:

Cole Palmer was not involved in this game, and it really, really showed. He is still on holiday after playing a key role in England's run to the Euro 2024 final, even scoring in the ill-fated showpiece against Spain.

The Three Lions attacker is a ray of light for this Chelsea team, capable of opening up defences with superbly incisive passes, and also possessing the ability to score from pretty much anywhere.

Without him, there is precious little fluency to Chelsea's attack. They can create chances - and they did at times, particularly when Marc Guiu and Raheem Sterling combined in the second half - but they lacked a potent finisher here.

Palmer may not have helped keep the ball out of the net because of just how disastrous Chelsea were defensively, but he may well have played a role in making a game of it.

3. Raheem Sterling finding his feet:

Sterling won the penalty from which Nkunku scored his late consolation and was a handful down the left after his introduction at half-time.

He dovetailed well with Guiu and created multiple openings.

Sterling was, at times, guilty of a poor final ball but he was willing to take the ball and run at the Celtic backline, which was a marked change from Mykhailo Mudryk.

They were better with him in the team and he is one of few Blues players who can walk away with their head held high.

4. Enzo Maresca's error-prone tactics:

Could Maresca be sacked on the basis of pre-season?! It feels very unlikely, of course, because that would be truly unheard of.

However, a 2-2 draw with Wrexham pointed to severe problems, and a 4-0 thumping here will only ratchet up the pressure on the former Leicester boss.

He is going to have to find a way to adapt but as it stands, Chelsea look at sixes and sevens.

The high-pressing, high-line approach demonstrably works for the best teams in the world but this was something else; Chelsea didn't know when to press, when to sit, or how to track back. Those are the three basic tenets and they failed at every single one.

There were a couple of very good chances manufactured in both halves, but it matters little if you constantly leave the door open at the back.

Chelsea are known for being consistently trigger happy and Maresca has to find a way to get this bloated squad into shape before their first Premier League game, which comes against Manchester City.

On this evidence, that could be another thrashing.

5. Carney Chukwuemeka's brilliance: 

In the first half, Chukwuemeka was undoubtedly Chelsea's best player. At the age of 20, he has already racked up 27 appearances for the club since his move from Aston Villa and he looks a mature, rangy midfielder already.

His energy and ability to play forward, while receiving on the turn, make him invaluable to creating chances in the final third.

One has to think that he will be a key player under Enzo Maresca as the season picks up steam, especially if he can take this form into competitive games.

6. Mykhailo Mudryk showdown continues...

His substitution at half-time for Raheem Sterling may well have been planned in advance but it remains almost impossible to claim that the Ukraine international has ever played well for Chelsea.

He has been one of the more disappointing buys in Premier League history - he has scored five goals in 31 games after being signed for £88.5m ($113m) - and yet again, he was completely anonymous.

Mudryk had a flash of going beyond two defenders and crossing, but it was to nobody, and he regularly failed to track his man and help his defence.

It may simply be ring-rust but he struggled at the European Championship too. Time is running out for him to prove his worth. On this evidence, he may not be able to do it.