He said: "I didn't know what to think when my penalty kick hit the crossbar. At first, I thought it crossed the line but the referee said it didn't so it was really disappointing as I walked back to the rest of the players.
"I'm lucky Artur (Boruc) made the saves and got us through. He came to the rescue and I was very relieved to see him make them. It was a great feeling to qualify."
However, even as Naka reflected on the joy of edging out Spartak, he was still upset at himself for not making a bigger impact.
He said: "I missed two good chances during normal play and Jan Vennegoor of Hesselink missed a penalty. On another day, we would have scored the goals and won the game.
"However, I am not happy with missing the chances. I've been thinking about it a lot since the end of the match.
"But it was a really difficult game. We had better chances than Spartak, but they passed the ball well and played on the counter-attack. They have quick players and were dangerous.
"After taking the lead we were looking to get to half-time with the one-goal advantage, but then we lost a bad goal."