Luis Suarez broke Liverpool hearts when he left for Barcelona in 2014 and he left them hurting again with the opener here in his first game against his former club.
But it was the brilliant Messi who crushed them with his delightful double.
There was some surprise when the Liverpool team sheet was revealed.
Roberto Firmino was struggling with a groin problem so it was not his absence but more so the fact Naby Keita replaced him and Gini Wijnaldum started up front.
Klopp also opted for James Milner over skipper Jordan Henderson.
With the inclusion of Joe Gomez instead of Trent Alexander-Arnold at right-back, this was a clear sign that Klopp was wary of the threat of Barcelona.
It is not often he is but he had a right to be considering their front line of Lionel Messi along with ex-Reds Suarez and Philippe Coutinho.