Erling Haaland scored a hat-trick as Manchester City thrashed Chelsea 4-2 in front of over 70,000 fans at Ohio Stadium, ending their US pre-season tour on a high. The result highlighted the Norwegian striker’s continued potency and raised questions about the defensive vulnerabilities of Chelsea under new manager Enzo Maresca.

Haaland showed no signs of the muscle injury he picked up in the 2-2 draw with Barcelona, scoring twice in the first five minutes to leave Chelsea reeling. The first goal came from a penalty after he was brought down by Levi Colwill, and the second was a result of a defensive error by Moisés Caicedo, allowing Haaland to pounce on a loose pass and finish clinically.

Chelsea's best chance of the first half fell to Christopher Nkunku, who got behind the City defense, but Stefan Ortega, starting ahead of Éderson, was equal to it and deflected his effort wide. While Chelsea did pull two goals back in the second half, the first hour was a stark reminder to Maresca about the work he still has to do.

Here are five key takeaways from the match:

Enzo Maresca's Defensive Concerns

Maresca, who is a former assistant coach at Manchester City, will be concerned by the way Chelsea’s starting XI, which was considerably stronger than City’s, were undone by a series of costly mistakes. After conceding goals while playing out from the back against Wrexham and Celtic in this pre-season, they found themselves 2-0 down inside five minutes after successive cock-ups.

First, Tosin Adarabioyo, the new Chelsea center-back, kicked the ball straight to Jack Grealish, leading to Haaland winning and scoring a penalty. Then, Caicedo misplayed a pass, gifting Haaland an easy finish for his second goal. The same theme continued in the second half, sadly, with City scoring twice more.

Even if this is only pre-season, Maresca must be concerned with Chelsea facing City in their Premier League opener in two weeks’ time. For their sake, you hope this was them getting those errors out of their system early.

James McAtee Impresses

James McAtee, a young player previously on loan at Sheffield United and a target for Chelsea, looked particularly impressive at times, showcasing his talent with a series of skillful maneuvers, including a moment where he skinned Mykhailo Mudryk to create a chance in the first half.

It was clear that Pep Guardiola was using this pre-season to take a closer look at McAtee before deciding on his immediate future. Chelsea will also be impressed with Oscar Bobb, who scored City's third goal.

Tosin Adarabioyo's Mistakes

There was a Chelsea fan with a homemade banner here which read: ‘Trev deserved better.’ That is in reference to Trevoh Chalobah, left at home as the club work on selling their homegrown central defender. Chelsea could not resist going for Adarabioyo in the summer, given he was available on a free transfer. But the 26-year-old does have a mistake in him.

As well as his mistake for City's opener, he later acted way too casual when chasing back to collect a ball, allowing McAtee to sneak in and steal it before testing Robert Sanchez. Adarabioyo's struggles against City will give Maresca food for thought.

Christopher Nkunku Struggles

Christopher Nkunku and Josko Gvardiol both played together for RB Leipzig and were having a good catch-up in between their training sessions. Here at the Ohio Stadium, they went up against one another. But for the first time in this pre-season, Nkunku could not get on the scoresheet. There was one moment when he got the better of Gvardiol by latching on to a brilliant pass from Enzo Fernandez, but City goalkeeper Stefan Ortega refused to let him slip the ball through his legs.

Nkunku is not yet fully fit, but says he is working towards it as he hopes for a big season in the Chelsea shirt after last year's injury-plagued campaign.

Romeo Lavia Shows Promise

One positive for Chelsea is how impressive Romeo Lavia has been in pre-season, often playing a pivotal part in their good play. It will be interesting to see how big of a role he can manage in the next campaign. It was his brilliant ball in behind for Noni Madueke that completed this 4-2 scoreline. Lavia will be looking to build on his strong pre-season performances as Chelsea prepare for the Premier League season.

A Positive Step for City

While it’s only a pre-season friendly, City’s performance against Chelsea will give them a confidence boost as they prepare for their upcoming clash against Manchester United in the Community Shield. The victory showcased their attacking prowess and will be a welcome relief after a disappointing series of results in their other pre-season matches. The team will now be looking to build on this momentum as they head into the new season.

City are next in action against Manchester United in the Community Shield at Wembley on Saturday before facing Chelsea again on the opening weekend of the Premier League season.