Elanga struck during the 3-2 win on Tuesday night, with Arsenal striker Viktor Gyokeres grabbing an 88th minute winner for the Swedes.
Elanga told local reporters in the mixed zone afterwards: "I'm happy, damn it, I'm happy. I don't have to say much. I'm proud of the guys, we did it. We got our second chance, it was tough.
"Poland is very good, it was tough for us, but before the game we thought... we knew we would win today and that's what we did."
Put to him that he scored "a real dream goal", Elanga agreed.
He also said, "Yes, you could say that. The guys said: 'Are you left-footed or right-footed?' I said both, it doesn’t matter to me, but I’m really happy to score and proud of the guys, proud of Viktor (Gyökeres) and Gustaf (Lagerbielke) who also scored to help us to the World Cup.
"Now we’re going to the World Cup."