Klopp hailed his team's best performance so far after goals from Georginio Wijnaldum and Roberto Firmino established a comfortable lead that would have been bigger but for some wasteful Wembley finishing.
Rothen told French sports daily L'Equipe: "He's a player I was reluctant to start with".
Liverpool and PSG both take 100 per cent domestic records into a blockbuster Anfield clash and Scotland skipper Robertson is under no illusions about the size of the challenge facing Jurgen Klopp's side. I think it is a moment where you have to show faith in the squad. "The result is the most important thing and the result is flawless".
The England global said he had no problem with the selection choices made by Klopp.
"Winning here is so hard, so unbelievably hard, not that I would never expect that only because we came here and tried to our bit because you need the performance that the boys delivered today".
Meanwhile, the Liverpool manager is unsure on the severity of Firmino's facial injury that forced him off in the 74th minute on Saturday following a duel with Jan Vertongen.
"I think if you compete and they were better you say congratulations but I think we cannot compare, make a bracket - Watford was Watford, Liverpool you can win or lose and I am not saying anything about attitude". You always know our attacking threat will hurt the opposition and score goals, so for us as a team it's about defending properly and that's everyone from the goalkeeper to the striker.
"We maybe have an injury with Roberto, something with his eye we'll see", said Klopp. Because we came here and tried to do it, you need a really outstanding performance - and that was what the boys delivered today.
"I don't know exactly what it means but to focus on one competition can only be if maybe you are already out of the competition almost".
"On another side, a good thing for us is that we've got a lot of players that can cause them problems".