LONDON • Jurgen Klopp looked around a distraught Liverpool dressing room at Wembley in February and urged his team to use defeat in the League Cup final as motivation to go one better in future.

The message continues to resonate on the evidence of a comfortable and comprehensive 3-0 defeat of Derby County in the third round on Tuesday.

The class of Philippe Coutinho and, increasingly, Roberto Firmino made deep impressions.

The Brazilian duo dissected the Championship team in a commanding second-half display illuminated by fine goals from Coutinho and Divock Origi, after Ragnar Klavan had given the visitors a first-half lead.

"Could we have done better? Yes. Is that important? No," said a satisfied Liverpool manager. "The opponent was ready for each opportunity but we didn't give them any.

"In the first half we could have been better with the last pass and in the second we could have been better with the counter-attack but we scored the goals.

"This is a very important tournament for us, not only because I say it but for the players too and we have to show it is important."

In another match, Arsenal enjoyed an equally comfortable 4-0 stroll over Nottingham Forest.

Denmark striker Nicklas Bendtner lined up for Forest against his old club, but it was Arsenal's new arrivals who shone.

Granit Xhaka rifled in the opener from distance and Lucas Perez scored a penalty and a fine individual goal. Alex Oxlade-Chamberlain netted the fourth in stoppage time.

For Arsenal manager Arsene Wenger, victory also justified his team selection and the calculated gamble of starting with only three players aged above 24. He had six teenagers on the bench with Arsenal's starting XI and seven substitutes wearing shirt numbers adding up to 618.

The Frenchman said: "I told the players before the game that we went to Sheffield Wednesday (last season) and lost 3-0 because we were not ready mentally for the commitment of the Championship.

"Our history helped us tonight to start in a much stronger way."

THE GUARDIAN, REUTERS