Marc-Andre ter Stegen was delighted his man-of-the-match display helped Barcelona progress to the final of the Supercopa de Espana.
Ronald Koeman's side won 3-2 on penalties after a 1-1 draw with La Real in the first semi-final in Cordoba.
Mikel Oyarzabal's penalty cancelled out Frenkie de Jong's header in normal time and there was little to split the sides in an end-to-end contest.
Ter Stegen produced six saves in 120 minutes including an impressive one-on-one stop to deny Alexander Isak and a flying one-handed save from Joseba Zaldua, and he even appeared to get fingertips to an Adnan Januzaj free-kick that clattered off the post.
The Germany international saved Sociedad's first two penalties in the shoot-out, including from Oyarzabal, before Riqui Puig's decisive effort sent the Catalans through.
Ter Stegen, who said he had not "studied" for a possible shoot-out, was left frustrated that he did not quite reach Januzaj's effort to end the penalties earlier.
"I'm very happy with the game, but I could have saved one more penalty," he said.
"Real Sociedad were a really tough opponent. We deserve the victory. I always look to be at 100 per cent. You have to win these games, and I'm very happy to be able to help the team.
"In the first 25 minutes, they pressed really strongly and did it really well. It was tough for us to get out, but bit by bit we found space and played between the lines.
"They were tiring and we were able to dominate the ball more."
Oyarzabal sent Ter Stegen the wrong way with his penalty in normal time, converting for the 15th time in a row from the spot, the best such run of any LaLiga player since the start of 2015-16.
However, as he tried a similar stuttered run-up in the shoot-out, Ter Stegen waited before flying to his right to make the save.
"What can I say? Losing like this hurts even more," said Oyarzabal. "To have the opportunity and lose on penalties, which is part lottery and part success...
"If I had to take a penalty tomorrow, I'd do it in the same way. The longer you wait, the fewer options the goalkeeper has. In the end, this time, maybe I rushed it a bit."