Coutinho was so ineffective in Sunday's 2-1 win over Burnley that with the game finely balanced at 1-1, Jurgen Klopp replaced him with Ben Woodburn, a largely untested 17-year-old. Just as significant, few in the crowd even questioned the decision, such was Coutinho's lack of impact on the game.

It's been quite the fall from grace, as Coutinho is widely regarded as Liverpool's best footballer (although some would argue that Sadio Mane has now eclipsed him) and they just do not have the squad depth to be able to get away with key players not performing. That Klopp's only alternative to Coutinho was a teenager yet to make a Premier League start shows just how much they rely on him.

One or two decent performances apart, Coutinho has been hugely disappointing so far in 2017 and it's surely no coincidence that the team have been, too. Liverpool no longer have Luis Suarez, Steven Gerrard, Raheem Sterling and Daniel Sturridge as headline acts, so they need Coutinho to step up and be the man. When he doesn't, they can be vulnerable.

Earlier in the season, Coutinho dazzled and finally looked to have added some much-needed consistency to his previously sporadic brilliance. Since returning from injury he's also shown consistency, but unfortunately he's been consistently poor. The good news is that Liverpool's next opponents are Manchester City, a team that invariably brings out the best in Klopp's mercurial No. 10.

Coutinho seems to love playing against City. His performances against them are usually top quality, so there is no better team for him to be facing while he goes through this testing period. Players often have "lucky" stadiums or opponents -- places or teams that always seem to bring the best out of them -- and for Coutinho that is definitely Manchester City. If this game doesn't get him back on track, then you have to wonder what will.

It isn't just Coutinho who seems to enjoy facing City, though. Despite the gulf in quality, Liverpool's recent record against the Mancunians is largely very good, particularly at Anfield, where they haven't tasted defeat against City since 2003.

They've had some losses at the Etihad, but have usually performed well there, not the least of which last season when they utterly demolished Manuel Pellegrini's side in a devastating exhibition of Klopp's famed "gegenpressing." Liverpool ran riot that afternoon and the relentless pressing and quick counter-attacking of Roberto Firmino, Adam Lallana and Coutinho simply blew City away.

Liverpool will be hoping for a repeat of that this weekend, but they no longer have the element of surprise they had in this fixture last year. City looked utterly shell-shocked and did not know how to deal with Liverpool's high tempo, all-action style that day. That won't be the case this time because many of their players will remember the humiliation they suffered a year ago and, of course, Pep Guardiola is as familiar as anybody with Klopp's style of play due to their years competing with each other for titles in Germany.

Philippe Coutinho has been disappointing in 2017 and it's no coincidence that Liverpool have been, too.

The last meeting between the sides was a cagey affair this past December that Liverpool edged through Georginio Wijnaldum's fine header. Coutinho missed that game and Liverpool were not at their fluent best in attack, but they defended superbly to record a win that sent them into the New Year in second place and just six points back of leaders Chelsea. Things have gone badly wrong since then, of course, but that's been due to an inability to beat teams in the bottom half and Klopp's men tend to make games against the better sides -- such as City -- look quite straightforward.

Liverpool's impressive record against the top teams is certainly no fluke. They are at their best against opponents that want to go toe to toe with them and try to attack. City only know one way to play and that is to get the ball down and attack. As soon as you do that against Liverpool you can be exposed, as Arsenal and Tottenham have found out in recent weeks.

Guardiola has been known to tweak the way his team plays when he comes up against Klopp and they might well play more long balls than usual this weekend, but it won't be anything like what Liverpool have had to deal with in recent away losses at Hull and Leicester, or indeed in last week's home win over Burnley when they faced an aerial bombardment. Even though it is proven to be the best way to beat Liverpool, City will not sit back and defend -- especially not at home.

With that in mind, Liverpool have every reason to feel confident ahead of their trip to Manchester, but obviously it won't be an easy game given the world-class talent City have in attack. Klopp's unbeaten record against the rest of the top six this season has to come to an end at some point and it might well be this Sunday, as City are well capable of beating anybody when they perform. They will be keen to bounce back from their Champions League elimination at the hands of Monaco, so Liverpool will need to be wary of a backlash.

It promises to be a fascinating encounter because neither side can defend but both score goals aplenty. Liverpool's style is perfectly suited to hurting a team like Manchester City. If they perform at their best, they will probably win, even though player for player City have more quality, certainly in advanced positions. For Liverpool to be anywhere near their best, though, they will need Coutinho to snap out of this funk.

It's time for "The Magician" to stop doing his disappearing act and get out his box of tricks once again.