IAN LADYMAN: Jurgen Klopp's X-factor at Liverpool is impossible to replace

Standing on the touchline, hands on his head with the smell of sulphur in the air, Pep Guardiola had been here before.

Looking out at a swirl of red – a blizzard of red – threatening to engulf his team of champions, a Liverpool team propelled forward on a diet of emotion, adrenalin and purpose.

This has been Liverpool during Guardiola’s years in the Premier League with Manchester City. This has been Jurgen Klopp’s Liverpool. Soon it will be different and Guardiola – deep in his coach’s heart – will know that better than most.

Whatever happens between now and the season’s end – whoever wins this year’s Premier League – Guardiola will watch Klopp walk away knowing that he never quite managed to solve the puzzle.

Guardiola has more league titles to his name and as such can lay claim to having dominated the English top flight in a way nobody previously had in the modern age. Still, though, he has never managed to find the solution to the deep and complex challenges presented to him by Klopp’s Liverpool teams.

Here, as the home team recovered from a first half that had seen them bettered, Guardiola simply watched a similar story unfold. As the saying goes, he had seen this movie before.

Liverpool playing with an intensity it was impossible to match in an atmosphere not bettered anywhere in Europe. Liverpool playing in a way that didn’t really make sense given the rather patched-up nature of their line up. Liverpool presenting a challenge as emotional as it was tactical. Liverpool, in short, playing in the mirror image of their manager.

And this is the cold truth of it for Liverpool as they attempt to move forward without Klopp from the end of this season. Speaking about this last Friday, Klopp was modest. Of course he was. The