Andy Robertson a doubt for Napoli clash?

Jurgen Klopp has confirmed that Andrew Robertson has suffered a knock ahead of Liverpool's opening Champions League group game of the season against Napoli.

The left-back did not train with his teammates before flying to Italy on Monday and will be assessed on Tuesday.

Liverpool begin the defence of their Champions League crown at the San Paolo, where they lost 1-0 in last year's group stages.

Speaking to the club's official website about the injury, Klopp said: "Robbo didn't train today and we have to see.

"It is not a major thing, it was more precautionary today, but it is not 100% sure [he will be available].

"We will have to test it tomorrow and then we will see."

Robertson played an indispensable role in Liverpool's route to European glory last season, making 12 appearances in total.

Klopp's side will also face Belgian outfit Genk and Austrian club RB Salzburg in a group that they are expected to win.