European champions Liverpool were unable to get their Champions League campaign off to a bright start as they fell to a 2-0 loss at Napoli on Tuesday. Dries Mertens scored from the penalty spot following a poor Andrew Robertson challenge, with Fernando Llorente sealing the three points in injury time following a Virgil van Dijk error.

Positives

There was always a clear and evident threat on the counterattack from Jurgen Klopp's men as they remained patient and didn't get forced into any errors. They were able to wear Napoli down as the game went on, and their quick passing was a constant pain for the Italian side to deal with.

Negatives

The Reds showed Napoli far too much respect on the ball and seemed far too laid back when they were in possession. The hosts were often able to reset themselves pretty efficiently, and one of the key reasons for that was Liverpool's slow pace, which always ensured they were living dangerously.

Manager rating out of 10

6 -- Klopp's realisation that his side needed more physicality in the middle of the park led to an interesting starting XI, and certainly got them out of jail more than once. However, the manager struggled to make the necessary changes, and while Liverpool showed a clearer attacking incentive in the second half, Klopp's hesitation with his substitutions didn't help matters.

Player ratings (1-10; 10 = best. Players introduced after 70 minutes get no rating)

GK Adrian, 8 -- Made a vital double save from Fabian Ruiz in the seventh minute before producing one of the saves of the season in the 49th from a Mertens effort. Got a strong hand to the Belgian's penalty but couldn't keep it out.

- Champions League group stage: All you need to know
- ESPN Champions League fantasy: Sign up now!

DF Trent Alexander-Arnold, 7 -- Maintained a strong balance of attacking pace and phenomenal timing with his defensive duties. Has a great instinctive touch and made a key interception in the 11th minute.

DF Joel Matip, 7 -- Made a key clearance in the 25th minute and while he did drift forward on occasion, the Cameroon international remained solid at the back throughout the game.

DF Virgil van Dijk, 6 -- Made a rare yet crucial mistake for Napoli's second goal. Was in complete control at the back right up until injury time, which let him down after 90 minutes of solid play.

DF Andrew Robertson, 5 -- Lively down the wings but had a poor end product. Picked up a 57th-minute yellow card for a tame yet silly pull and gave away the penalty with a simple mistake.

MF Jordan Henderson, 6 -- The captain rarely put a foot wrong, but in equal measure he didn't have much of an influence on the state of play. Substituted off in the 87th minute.

MF Fabinho, 7 -- Proved why he's considered to be one of the most consistent defensive midfielders in European football. Seemed to get drawn into Napoli's games at times but was one of Liverpool's brighter sparks.

MF James Milner, 6 -- Looked very composed in the first half but the frustration in his game was clear as time went on. Picked up an avoidable yellow card in the 61st minute for being slightly too physical.

FW Mohamed Salah, 6 -- Forced a great save from Alex Meret in the 65th minute but was largely kept at bay by a confident Napoli backline. Was always energetic and didn't fade down the stretch.

FW Roberto Firmino, 6 -- Was swarmed by Napoli's defenders time and again. Seemed to struggle with the lack of space and wasn't able to get into his usual rhythm.

FW Sadio Mane, 6 -- Saw a nice effort saved in the 21st minute but seemed to go downhill from there. Had a poor final touch in the 55th minute when he could've set Salah up perfectly.

Substitutes

MF Georginio Wijnaldum, 6 -- Was brought on to get things moving for Liverpool from an attacking standpoint but was boxed out every single time he got on the ball.

MF Xherdan Shaqiri, N/R -- Came on with three minutes remaining and didn't have time to make an impact.