Despite losing a key player, Jurgen Klopp had seemed incredibly relaxed and confident in the build-up to the City game, and after seeing the way his team went out and performed we now know why. Liverpool's first XI has more than enough quality to absorb the loss of the Brazilian, particularly in games like last Sunday's when energy and desire take precedence over guile and flair.

Klopp's front three are as good as any in the Premier League, and he can call on either Alex Oxlade-Chamberlain or Adam Lallana to fill Coutinho's spot in midfield. Different types of players than the Brazilian and clearly not as talented, both are still high-quality international footballers in their own right. Liverpool are fine -- for now, at least.

The problem could be in the weeks ahead if they were to suffer one or two injuries, or when Klopp needs to start rotating his lineup when the Champions League rolls around again. That is when the loss of Coutinho might be most keenly felt, unless of course the Reds can strengthen their squad before the end of this transfer window. The win against City, though, highlighted just how difficult it will be for Klopp to do just that.

Even without Coutinho, Liverpool's front six are strong and they are so well schooled in Klopp's methods that finding players who are good enough to even compete for a place, let alone improve the starting lineup, is more difficult now than it has been for many years. That's a good thing and bodes well for the future, but not necessarily for the present, and supporters hoping to see new arrivals this month may end up disappointed.

There aren't too many players out there who are better than what Liverpool already have, and fewer still who would be attainable midseason. Leicester's Riyad Mahrez might be available and he has the ability to grace any team in England, yet none of the top clubs have shown any serious interest in him and there has to be a reason for that.

Why would Liverpool not be in for a talent like Mahrez, especially now when they have money to spend and are in need of more creativity and squad depth?

The breathless, high-octane performance against City provided a big clue, as did comments made by Oxlade-Chamberlain in the build-up to the game. The former Arsenal man took some time to find his feet after his summer move to Merseyside and he provided some insight into how difficult it can be for a new player to learn Klopp's way.

"The biggest thing I've had to learn is how this manager likes to stop situations at source," he said. "When a team is in sync to do what a manager wants and you have one player who has come in and is doing it slightly different it breaks the whole chain and it doesn't work for everyone. We press high and if one person is not doing it right it makes everyone's work a waste of time. Just little things like that I had to learn and it can take some time."

The way Liverpool set about pressing City on Sunday was a sight to behold as in spells they ran all over the previously unbeaten league leaders and ultimately blew them away with three goals in a blistering nine-minute spell in the second half. It takes effort, desire and stamina to do that, but it also takes weeks -- and in some cases months -- of coaching.

Liverpool's high press is not just about players running around like their hair is on fire (Andy Robertson's maniacal charge from one left-back position to the other notwithstanding). It is finely tuned and highly organised. Hunting in packs, closing off angles, forcing the opposition to go where you want them to and where you can pick them off. It takes countless hours on the training pitch to master it, and asking a new player to come in and be able to do that straight away is unrealistic.

While someone such as Mahrez would have little trouble creating and scoring goals in Liverpool's front three, what he would be expected to do out of possession would almost be like learning a whole new sport, as it is so alien to anything he has been used to at Leicester. Signing a player from a team that plays a similar pressing style would make the transition easier, but that is narrowing down what is already a small pool in January.

Therefore any new attacking player would be unlikely to make much impact straight away and it could be March or April before that player is fully up to speed. Not ideal, but it could still make all the difference if it allows Klopp to rotate his starters and keep them fresh for the latter stages of the Champions League.

Liverpool look to be on course for a good season even without further strengthening in January, but if they could somehow bring one or two in, "good" could yet become "great" as the Merseysiders showed on Sunday that they are a team nobody will feel comfortable about facing over two legs.