Can Liverpool regain their aura of invincibility in the Premier League?

Liverpool kick off their Premier League title defence on Saturday with an intriguing game against newly promoted Leeds United, and even their fans are wondering if the champions can regain their aura of invincibility.

Manager Jurgen Klopp never wavers in his belief in players he calls "my mentality monsters" and is convinced they will rediscover the electric form that left their rivals for dust last season. But there are nagging doubts.

Since the title was secured on June 25, Liverpool have kept only one clean sheet in eight matches. At times, they've looked strangely fragile in defence, especially in losses to Manchester City and Arsenal. U.S. superstar Christian Pulisic also ran them ragged towards the end of the 2019-20 season, albeit in 5-3 win over Chelsea. Even at Wembley in the Community Shield shootout defeat to the Gunners, there was a feeling that the team were still a little flat, their batteries not quite fully recharged for the season ahead.

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A few days before that game, errors by Fabinho and Joe Gomez had allowed Red Bull Salzburg to race into a 2-0 lead before young Rhian Brewster scored twice to salvage a draw in a preseason friendly in Austria.

It's easy to dismiss these hiccups and sloppiness as an understandable "easing-down" after the glittering prize had been secured. Players are not machines. There was bound to be some loss of intensity after the title party.

But as managers often warn us, form cannot be switched on and off like a tap. So perhaps Liverpool fans are wondering if the team can reignite the fire against Leeds, a fixture that renews a rivalry going back to the feisty clashes in the 1960s, when Bill Shankly and Don Revie were the iconic managers involved. Later there was the infamous Wembley match when Leeds' Johnny Giles stayed on the pitch after flooring Liverpool's Kevin Keegan with a perfect right hook, only to see Keegan himself and Leeds skipper Billy Bremner shown red cards for a later clash. And that was in the Charity Shield, as it was then known!

The modern buoyant Leeds, back in the big time after 16 years and led by the innovative Marcelo Bielsa, look set to offer a significant test of where Liverpool are right now.

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We can be certain that Klopp & Co. will have stepped up their preparations by several gears in the past few days with some ferociously intense sessions at Melwood. They could look a far sharper outfit than the one we saw in the Community Shield, when the famous front three of Mo Salah, Roberto Firmino and Sadio Mane made little impact.

Another question hanging in the air is whether the squad should have been freshened up a little more. The only excursion into the transfer market so far has been for left-back Kostas Tsimikas, an £11.75m buy from Olympiakos to act as cover for Andy Robertson.

It's no secret that Klopp would love to add Bayern Munich's classy technician Thiago Alcantara to his midfield, but that transfer saga might drag on until close to the Oct. 5 deadline. Signing Thiago would change the midfield dynamic. It could also prompt the departure of Georginio Wijnaldum, who is out of contract next summer and is wanted by his old Dutch national team boss Ronald Koeman at Barcelona.

One of Liverpool's greatest players, Graeme Souness, says that the trophy-winning teams he played on in the 1980s always welcomed a fresh face or two every summer to keep everyone on their toes. Staleness can breed complacency at any club.

Another Anfield issue is whether Klopp should buy another central defender. Dejan Lovren has left for Zenit St. Petersburg, so is there enough cover for first choices Virgil Van Dijk and Joe Gomez? Joel Matip seems to miss many games with injury, and switching Fabinho to defence robs the midfield of its natural "holder".

Liverpool finished a massive 18 points clear of Manchester City last season and did not lose a Premier League game until February 29 at Watford. They were champions with a record seven games to spare, and may be insulted to find City, who lost nine times, considered as favourites this time.

Chelsea, who have splashed the cash on some high quality signings, clearly mean business this season, too, as do an improving Bruno Fernandes-inspired Manchester United. Spurs and Arsenal will improve on last season's subdued campaigns.

So the signs are there for Liverpool to find it much tougher to repeat last season's 99-point runaway success story. Now they are the hunted.

Against that backdrop, Klopp will want to build a Liverpool dynasty, and you sense nothing would give him greater pleasure than to foil Manchester City's attempt to regain their crown, just as he frustrated Bayern Munich a couple of times with title wins at Borussia Dortmund. The first three games -- against Leeds, then Chelsea and Arsenal -- might tell us whether Liverpool are still on something of a title hangover or back to their frightening best.

It is the hunch of this observer that they will again take a lot of stopping.