It was one of the iconic images of Liverpool's run to Champions League glory.
In their astonishing comeback from 3-0 down against Barcelona, Andy Robertson playfully ruffled Lionel Messi's hair as the superstar claimed for a free-kick.
That kind of no-nonsense attitude is what has made the Scotland captain an idol for the Kop - but the left-back wishes he hadn't done it.
He told the Daily Mail: "When I look back on things I don’t really regret anything because I feel as if everything is experience that makes you what you are.
"But I do look back on that moment with Messi as one regret. I don’t like seeing it. When I saw it afterwards I was gutted.
"We all had the attitude that day that nothing was standing in our way to get to that final and we created that atmosphere around the stadium and me and Fabinho were tracking him and there was a tangle of legs and we were on the floor. To do that to the greatest player that has ever played…
"I have nothing but respect for him and Barcelona, but we went into that game with the attitude that we were 3-0 down, we needed a miracle, we needed something special and if that little thing stopped the best player in the world playing to his highest potential…
"But I do regret it. That’s not me as a person. That’s not my personality. But that night a lot of things happened that you don’t really remember. There was no thought process behind it. We were right up for the game. The fans were roaring and you get caught up in it. You’re a human being. We were 3-0 down in the semi-final of the Champions League, which we wanted to put right from the season before. It was the loudest changing room I have been in before the game. You could see the focus and the determination in all of us and maybe I went over the line."
