A Gabriel own goal earned Saints a 1-0 win to knockout the holders.
Hasenhuttl later said, "We had in the first half more punch and more power.
"In the second half it's normal they have a lift. We must make the second goal. We made one or two chances - Shane Long should have got a penalty.
"We had early ball wins, but our last decision-making was not always the best. In general our work without the ball was good.
"It was a good team performance today."