Jürgen Klopp believes tonight's Champions League clash with FC Porto will tell him much more about his Liverpool side than most other games - but he's adamant the competition within the squad means whatever line-up he selects, there'll be zero complacency.

The Reds hold a commanding 5-0 lead from the first leg of the last-16 tie after an emphatic victory at the Estadio do Dragao three weeks ago.

However, Klopp is eager to point out the dangers of an ease up in performance level against a Porto side who will be determined to hit back at Anfield.

And he feels the strength and depth of his squad, and the subsequent competition for places, means whoever lines up this evening will have a point to prove.

He wrote in ‘This is Anfield’: "This is a fantastic test for us, a big challenge, because it doesn’t just test our ability, our skill, our fitness; it will test the most critical attribute of any side that wants to be successful – our mentality.

"How all of us – players, staff and supporters – approach tonight will tell me more about where we are in our development than any Premier League game against a Manchester City, United, Spurs and so on. We are in a positive way in this moment, but these are the moments of greatest danger. These are the moments when you can really learn about an individual’s mindset. If I was in the FC Porto side this evening I would be looking forward to this match more than any other of my professional career. I would see the opportunity that is there. So, we must do more than simply mirror the passion and desire they will show. We must surpass it, we must be at a higher level – players, staff and supporters.

"We must prove tonight we want it more than they do; show that we are ruthless and relentless, on the pitch, in the dugout and in the stands; be together as one in this approach. What I have really liked, since the first leg concluded, is that I have seen in the players an understanding that there is a job to be done and that they know they cannot ease off the accelerator for even one second.

"The healthy competition within our own side makes this the case. Never mind opponents, the desire not to be left behind within our own group means they keep reaching and reaching for the next level. Take the team selection and squad selection for the weekend just gone, against Newcastle, as an example for what I mean in this moment. Can I explain to Simon Mignolet why he doesn’t start, based on his own level of performance? No! Or to Danny Ward why he can’t even make the bench? Can I tell Joel Matip, Joe Gomez or Alberto Moreno that their level of application and ability doesn’t warrant a starting position? I cannot! For Ragnar Klavan, who performs to an outstanding level, I am unable to find a subs spot in this moment.

"This applies right through the team and squad. Lallana, Milner, Solanke, Ings and so on and so on, just using the last weekend as an example. These lads are pushing each other to perform at their maximum every single day. It is why, as a manager and as coaches, picking the team and the squad is both the easiest and hardest task of the week. Easiest because I have total faith in every one of the team that when given the opportunity to play, they take it and make the most of it. But it is also the hardest task because all these players deserve to be playing – not one has given me an excuse or a reason to say 'Sorry, you haven’t earned it for today.'

"If we continue in this way, with the entire squad displaying the ability and attitude that means they should start every game, we have a real chance of being successful together."

Pick up your copy of 'This is Anfield' at the stadium tonight, or subscribe online by clicking here.