In episode six of All Or Nothing, the documentary that follows Manchester City's record-breaking 2017-18 season, manager Pep Guardiola discusses Champions League last-16 opponents Liverpool with his assistants.

"They scare me," says Guardiola, in reference to the attacking threat posed by Jurgen Klopp's team. "They're dangerous, I mean it."

It is a telling admission; a rare expression of uncertainty and fear from a man who spends much of the documentary's eight episodes demonstrating an unwavering confidence in himself and his team.

As we know, these seeds of doubt would develop into two chastening defeats for City over the two legs that followed, providing evidence of why the Liverpool manager's biographer Raphael Honigstein says Klopp's teams are "Kryptonite" to Guardiola's sides.

The rivalry - friendly yet fierce - began in 2013, when Klopp's Borussia Dortmund ruined Guardiola's Bayern Munich debut in the German Super Cup and served notice that, perhaps, there was a way to successfully combat the Spaniard's seemingly imperious brand of football.

Since that game, the two have faced each other 13 times, with Klopp the only one of Guardiola's regular opponents to have won more games against the Spaniard than he has lost.

Of course, Guardiola can always point to the trophy cabinet if he feels the need for a riposte. Of the two managers, it is he in most need of a healthy stash of polish.

Born in Germany, continued in England

Pep Guardiola (left) has won seven league titles and two Champions Leagues as a manager, while Klopp won back-to-back titles at Dortmund and has been a Champions League runner-up twice

Guardiola and Klopp faced each other eight times in German football over two years before the latter left Dortmund at the end of the 2014-15 season.

Klopp departed the Bundesliga with the tally between him and Pep at four wins apiece. To place this in perspective, Guardiola lost only nine domestic games in total during the two seasons he and Klopp were both managing in Germany.

Klopp would also have the final word between them on German soil courtesy of Dortmund's 2-0 penalty shootout win over Bayern in the DFB-Pokal semi-finals.

"When they were in Germany, Pep was in charge of a Bayern team who had dominance in abundance over the whole of the Bundesliga, including Dortmund," German football expert Honigstein told Football Focus.

"It was impossible for Klopp to compete on a level playing field. It also didn't help that Bayern and Guardiola pinched some of his players, such as Mario Gotze and Robert Lewandowski. Klopp wasn't really in a position to win the war but he could win battles - annoying and upsetting the Bayern dominance just for a little bit.

"It never got personal between the two of them. If anything, they were very complimentary of each other and their tactics. Their relationship was always marked by huge respect, admiration and I think the biggest compliment that Pep paid to Jurgen was frequently changing his set-up and even going as far as playing long balls to bypass the pressing because he was so wary of the power Dortmund could bring on the pitch."

Klopp was already 10 months into his Liverpool career when Guardiola switched from Munich to Manchester in 2016, rekindling a rivalry that began calmly but last season produced four barnstorming games featuring 18 goals.

The two teams head into this weekend's encounter - the 15th between Guardiola and Klopp - unbeaten in the Premier League and joint top of the table, City only ahead of Liverpool through a superior goal difference.

What is Klopp's approach? Fewer touches, more direct

 

Klopp's Liverpool were responsible for three of City's seven defeats during the 2017-18 season

The majority of managers, most of whom are not blessed with the playing talent available to Klopp, prioritise keeping City at bay. They play the percentages by packing defence and hoping to frustrate Guardiola's team.

It is this that led City to average 71.94% possession and 17 shots a game over last season's 38 fixtures. They are averaging 72.51% possession and 24 shots a game so far this campaign.

But containment is not Klopp's way. Like Guardiola, the German is a risk-taker, with a philosophy and tactical vision built around 'gegenpressing' - in essence an extremely high-energy, high press that aims to win the ball back deep in the opponent's half. Against City, he fights fire with fire.

"If you are brave, if you are ready to make mistakes, then you have a chance," he explained before the first leg of the Champions League tie between the two sides last season.

"It's difficult to be brave against them because you can suffer. Sitting back is not a solution against City. Be there where there is a chance to get the ball. If we can win it then we have a chance. If not? It is very, very difficult."

His approach didn't work at all in the first meeting between the two last season, which City dominated and won 5-0 at Etihad Stadium, although significantly Liverpool conceded four of those goals after Sadio Mane was sent off in the 37th minute.

However, Klopp's gameplan would yield much more positive results later in the campaign.

His side's high pressing in the league game at Anfield resulted in five City errors leading to shots, two of which resulted in goals, as City's defence was tested in a manner it rarely was throughout the rest of the 2017-18 season.

It was City's first defeat of the campaign and six more would follow, two of which Klopp would also inflict to knock Guardiola's side out of the Champions League.

And while high pressing is clearly a key component of Klopp's tactics generally, he appears to make a very specific tweak when his side come up against City.

In the six matches between the teams since the start of 2016-17, Liverpool have employed a faster, more direct approach when in possession.

In those six games, Klopp's side averaged 2.68 passes per passage of play, compared with 4.13 across the 2017-18 season as a whole. They also registered only four sequences of 10 or more passes per game against City, whereas their normal average is 17 sequences per game.

You might think that is because City are so good at breaking up possession, but in fact the Reds made more progress up the pitch against City - 15 metres on average for every passage of play - than their 10-metre average across the rest of that season's fixtures. Their ability to pounce at pace once in possession was something no other team achieved so successfully against the champions.

It is why, in All Or Nothing, Guardiola expresses his concern about how quickly Liverpool advance once they get into attacking channels.

So what will the managers' approaches be this time?

The view of Guardiola as an idealist, with only one way of playing, would suggest he will continue with the tactical formula that has proved so successful since the start of last season.

And, according to Honigstein, that is likely to be the case, although more because of the players available to him, rather than stubbornness or an aversion to straying from his tactical ideal.

"Guardiola is a very vain manager and wants to show that his way of doing things is the best and that his team can settle that account that Klopp opened with him," said Honigstein.

"But I wonder whether he would be tempted to change things up a little bit if he could.

"He has been unrelenting when it comes to doing things his way at Manchester City but he has shown in the past that he can be pragmatic when coming up against sides of the make-up Klopp has instilled at Liverpool and had at Dortmund.

"Maybe he would be more direct. But he doesn't have a Robert Lewandowski figure up front who can hold the ball up, so sending balls up top to the likes of Sergio Aguero and Leroy Sane is probably not an option. That means it is difficult to him to change his approach, even if he wanted to.

"That makes it easy for Liverpool to set up, because they know - more or less - what they will have to do to contain City. Ultimately it will come down to how much Liverpool can disrupt City.

"Both teams will fancy their chances but I think the Champions League ties are very much in mind and therefore you have to give Liverpool the edge."