Lionel Messi hit out at Barcelona supporters who whistled struggling Philippe Coutinho off the pitch.
The former Liverpool man was again well below par as he came up against his old club in the Champions League semi-final first leg.
Barca may have won 3-0 but the 26-year-old didn't make an impact.
That drew an awkward reaction from the home fans who let him know their thoughts as he was hooked on the hour mark.
Coutinho, who Barcelona signed for £146m last season, endured a miserable night and was withdrawn for Nélson Semedo.
He was whistled by the home support as he left the pitch - and Messi was upset by the treatment.
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“This is a time when we have to be more united than ever, both as players and fans,” he said.
“This is something we have to achieve together and it is not the moment to criticise anybody.
“It is ugly to see [the crowd] treat a team-mate like that.”
Liverpool manager Jurgen Klopp called Messi untouchable and knows the size of the task facing the Reds next week.
“In these moments he is unstoppable," said the German. "We couldn’t defend the free-kick. What a strike!”
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“He’s a world class player. The second goal was probably not the nicest in the career of Lionel Messi but it shows his skills, that he is even there in that moment.
“Apart from that I was happy in how we defended the whole Barcelona team. But I knew before that Lionel was a world class player and now I saw it again I am obviously not surprised.”
Klopp still defended his side, even though he admitted missed chances and a couple of lapses in concentration cost them so dearly.
“I said that I am really proud of them, that I liked a lot of things about the game.
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"How we defended, how brave we were - we were not always brilliant but very good and we played and controlled the game in moments.
“No one will be interested but a few football nerds because it is about the result and we lost 3-0 but I really think this was our best Champions’ League away performance.
"There will be a time when I can use the game forever to show the boys what is possible.”
“Obviously our season is for close, tight decisions. We had a chance for Mo at the end and 3-1 would be a better result and I would feel slightly different in this moment but it is 3-0.
"It showed we can have chances and these boys never give up. I love them but there is no party at the moment. “
