Real lost 1-0 on Wednesday night through a Jonathan David penalty.
Afterwards, Lunin said: “It's difficult to analyse it right after the game, but I think we lacked aggression, creativity and more fight. In the second half, we had more desire than in the first, which I thought was worse. In the second half, we improved.
“We always want to win and we know the colours we are wearing. There's no problem, we have to keep working and prepare for the next game. We have to continue along the same lines.
“I'm not going to analyse the first half, but it was a bad one. We have to analyse and improve in the next game because there's no time. There are many matches and we have to win.”
On being back in goal, he added: “Personally, I'm pleased to be playing again. On the other hand, I hope Courtois recovers. But the most important thing today was to win and we didn't manage that. I can't be happy because we always want to win and it doesn't matter who is on the pitch, the team comes before everything else.”