Set to spend a season on loan with Wellington Phoenix, the 26-year-old is looking forward to his time in the A-League but struggles to hide his delight when looking back at the time he tackled the Los Blancos.
"Not just to play Real Madrid but to play in the Champions League...for me it was my dream," Kopczynski told Goal.
"It was fantastic, a great experience. To play against Cristiano Ronaldo, Gareth Bale and receive the ball from them.
"We did a really good job in this game."
All the more remarkable about the clash and result, is the fact Warsaw did it in front of an empty stadium.
After suffering a 6-0 defeat at the hands of Borussia Dortmund, resulting crowd trouble meant UEFA forced them to play their next match against Madrid behind closed doors.
"One bad thing about this game was that our stadium was empty and it was maybe one of the biggest games in Legia’s history," Kopczynski reflects.
From matching it with one of the world's most recognisable teams, the defensive midfielder has opted to join the Phoenix for the coming season and admits he's taken a leap of faith with a club and league he knows very little about.
"In Poland and Europe we don’t know much about Asian or Australian leagues," he said.
"For us, it’s a completely different world. I’ve never seen a whole A-League game."
After finding game time increasingly hard to come by in Poland, Kopczynski felt the time was right for a new challenge.
Having never played club football outside of Poland, the challenge is an admittedly big one.
"It’s a big transition. It’s on the other side of the world...one of the biggest flights you can do," Kopczynski said.
"For me it’s big because I’ve never left Poland, only for holidays or games. I’ve spent my whole career in Poland and almost whole career with Warsaw.
"It wasn’t easy to make up this decision."
From Warsaw to Wellington, Kopczynski trades a club that has won the Polish league three years running for a Phoenix outfit desperate to turn their fortunes around.
Under new coach Mark Rudan, the Nix were knocked out of the FFA Cup in Kopczynski's professional debut for the club.
Though not the start he would have been hoping for, the midfielder's ambitions are high for both the club and himself.
"Our goal is to be as high as possible," he said.
"For me I want to do my best in this league.
"I came here to play because last half year in Legia was worse for me. Previous years I was playing a lot of games but then a change of coach and owner and my playing time was little."