LIVERPOOL, England -- There are two ways to assess Liverpool's 4-3 victory against Leeds United on the opening day of the 2020-21 Premier League season. It was either a sensational showcase of everything that makes the Premier League the most box office competition in world football, or it was a game in which the coaching manual was thrown out of the window and chaos ruled.

- Report: Liverpool 4, Leeds United 3
- Liverpool ratings: Salah the star with hat-trick
- Klopp: Liverpool vs. Leeds 'a proper spectacle'

The reality is that it was both. Liverpool offered a glimpse of the complacency that could derail their title defence before it even slips into gear while Marcelo Bielsa's Leeds, playing their first Premier League fixture for 16 years, displayed the naivety that makes them wonderful to watch, but suggests there will be plenty of nail-biting games for the club if they're to avoid relegation back to the EFL Championship this season. By the time Mohamed Salah sealed a hat trick with an 88th minute penalty -- his second spot-kick of the game-- there had been four disallowed goals (two apiece) and a series of missed chances by both sides.

"What a game, what an opponent, what a performance from both teams," Liverpool manager Jurgen Klopp said. "It was a proper spectacle, I loved that. But we have left space for improvement in our defending, but that is not unusual for a first game."

Although Klopp's champions ended the game with all three points, he will have seen plenty from the 90 minutes to leave him raging with his players behind the dressing-room door. Don't fall for the jolly, smiling perspective given to the TV cameras. As for Leeds, they showed a healthy lack of respect for their opponents and came close to a remarkable result. Yes, they lost, but they had enough chances to win it and their performance at Anfield will give the Premier League newcomers the belief that they can compete at this level and safeguard their place in the top flight, having fought so hard, and for so long, to get it back.

But let's start with Liverpool. Runaway champions last season, they recorded their 26th Premier League home win out of their past 27 games against Bielsa's side -- a result that extended their unbeaten league run at Anfield to 60 games since April 2017. The result is ultimately all that matters, and Salah's hat trick will also go down nicely, with the Egyptian wasting no time in getting off the mark for the season. But the positives won't help Klopp sleep any better when he starts to analyse the defensive issues that almost cost his team dearly.

Trent Alexander-Arnold was given a torrid time by Leeds winger Jack Harrison, who is on loan at Elland Road from Manchester City, with the wide man beating him easily en route to scoring a 12th-minute equaliser for the visitors after Salah's first penalty had put Liverpool ahead. Alexander-Arnold's defensive game has never been his strength, but Harrison exposed every weakness. And when the England full-back headed into his own net in the second half, it looked to have completed a nightmare afternoon; lucky for the Reds, it was ruled out for an offside decision earlier in the move.

Alexander-Arnold wasn't the only Liverpool defender to have a bad day. Joe Gomez was shaky at centre-half, while Virgil van Dijk -- the typically unflappable, peerless Van Dijk -- gifted Leeds their second goal when he was rushed into a mistake by Patrick Bamford, who scored to make it 2-2 on 30 minutes, cancelling out Van Dijk's 20th minute header.

Perhaps the selection of Naby Keita ahead of Fabinho in midfield contributed to the lack of defensive certainty, with Keita unable to provide the industry and awareness of the Brazilian. But there was a tangible sense of complacency at the back for Liverpool, something that had begun to creep in towards the end of last season. Teams now know that a fast counter-attack can catch Liverpool out, and Leeds did it time after time.

Maybe a lack of new blood in key positions has contributed to that complacency, too. Dejan Lovren was sold to Zenit St. Petersburg this summer, but as yet he hasn't been replaced. There's little pressure on Gomez or Van Dijk to perform, and even less on Alexander-Arnold, who has no obvious challenger at right-back. Leeds picked holes in Liverpool's defence all afternoon, so much so that the champions will need to be much sharper when they visit Chelsea on Sept. 20.

The fact that Liverpool won, courtesy of Salah's late penalty, is a testament to their quality and determination, but this team certainly has its weaknesses.

Leeds also have problems to address, but their start to the season was largely positive despite the defeat. Their incessant running, neat passing and work-rate will ensure more good days than bad -- their chasing of lost causes certainly unsettled Liverpool's usual rhythm on the ball -- but perhaps this defeat will accelerate a realisation at Leeds that their cavalier football needs to be toned down a touch in the Premier League.

Top teams like Liverpool will punish them for every mistake and over-adventurous pass, and they will concede plenty of goals, but Leeds have brought some fun and fantasy to the Premier League; their learning curve will be well worth watching.

So too will Liverpool's. They may be champions, but they have flaws to iron out. Just like Leeds, they will pay a price if they don't.