Real Sociedad midfielder Mikel Merino felt they paid for their inexperience after a 2-0 Champions League defeat at PSG.
PSG took charge of this round 16 tie via goals from Kylian Mbappe and Bradley Barcola.
Merino said: "The difference in these games comes down to the small details. It was a very competitive game, with two teams going head to head with similar styles. After their opener, our lack of experience was crucial. Gaps started to open up and that's great for them because they have really fast players.
“We saw a brave Real Sociedad today. We came here to win the game, against a strong team, but we hope in the return leg, with our fans, we can win it.
“We can take a lot of positives, but we need to learn from our mistakes as well. We have to have faith because we did a great job during a large portion of this game. We'll press high again, and try to win our duels.
“This side is showing huge resilience; we are having problems with injuries. We don't have the same players game in, game out. That shows the team is fully committed. Every player that comes into the team is super committed to their team-mates and willing to help the team."
