The on-loan Manchester City midfielder played a key role in the 2-1 win.
A flashpoint was Girona's late winner scored by Fran Beltran. The visitors insist Jules Kounde was fouled in the build-up by Echeverri.
The Argentine later said: "We are very happy with the victory. The team worked very well.
"Those were difficult months in Germany. I had a very bad time and today I'm here, happy and with the intention of getting back to the form that led to my being sold to City.
On Barca, he added: "They are the best team in the world. Obviously, we had to suffer, but the team played very well, ran a lot, and that's why we took the victory."
Later, after getting changed, Echeverri spoke with a waiting reporter from El Chiringuito.
And he admitted: "I don't know, I didn't see the play. Do you have it there? Yes, I stepped on him, but I was coming at speed. Maybe it was unintentional , but..."
Asked if he would have understood if the referee had called a foul, the Argentinian replied, laughing, " Yes, I would have, but it's no big deal. Luckily, they gave us the victory."