Sadio Mane, Georginio Wijnaldum and Mohamed Salah scored the goals as Klopp's men showed little sign of the nerves and mistakes in recent 1-1 draws with Leicester and West Ham.
Robertson believes the loss of the injured Jordan Henderson, Joe Gomez and Trent Alexander-Arnold is having an influence but feels he and his teammates have the capacity to respond.
A 2-1 defeat at leaves the Spanish coach to face the most difficult challenge of his City stewardship.
Thursday's defeat was the first time Liverpool had lost in the league season.
Klopp said he was wary of falling into the trap of talking up his team's chances with 18 games of the 38-match campaign remaining.
Mourinho and his Manchester United side visit Anfield on Sunday with Liverpool 16 points ahead of their bitter rivals.
Premier League leaders Liverpool boast a 16-point lead over their historic rivals at the top of the table just 16 games into the season.
A home match against bottom club Fulham on Sunday may just offer the opportunity to start to put that right by giving both Naby Keita and Fabinho crucial game time to build momentum and confidence.
The Reds' manager also acknowledged that they would have to defend better in the visit to Stamford Bridge.
The 26-year-old Egyptian star has scored just twice this term.
Klopp, who took over at Liverpool job in 2015 after guiding Borussia Dortmund to two Bundesliga titles, says he expects his players to fight to the last breath for the league title.
Alisson is a key signing for Jurgen Klopp who was desperate for a new goalkeeper to replace Loris Karius.
Liverpool manager Jurgen Klopp labelled talisman Mohamed Salah a "genius" as the Egyptian came back to haunt former club Roma in spectacular style with two goals and two assists in a 5-2 semi-final, first-leg demolition of the Italians at Anfield.
Klopp is credited with finding the system to bring the best out of Salah.
However, Klopp's revival of Liverpool has come from far more than rabble rousing.
Liverpool manager Jurgen Klopp warned his side will still have to "work like hell" to reach the Champions League semi-finals despite taking a commanding 3-0 quarter-final first leg lead over runaway Premier League leaders Manchester City.
Two of Europe's heavyweight managers, Klopp and Guardiola look destined to compete for the sport's biggest prizes for years to come.
Manchester United boss Jose Mourinho has the tough task of keeping Liverpool's Mohamed Salah quiet as Jurgen Klopp's entertainers roll into town at the weekend -- with second place in the Premier League the prize on offer.