It was the 31-year-old Abidal's first-ever goal for Barca after 130 appearances and only the third of his professional career having netted two cup goals for previous club Lyon.
Guardiola said of the Frenchman: "He's been spectacular. As much at centre-back as full-back, he's in an impressive spell of form. Wherever we put him, he always plays well. I'm very pleased for him."
Abidal, whose side will now face either Getafe or Real Betis in the last eight of the cup, said after the game in AS: "We're going away very happy because it was a very difficult tie that we've come through.
"It's been a long time since I scored and now that it's a new year I hope things will change and I can continue scoring goals this season.
"I already know that when I have chances to shoot like this that I have to do it more often."
He added: "I've played at centre-back, full-back...the only thing left is to play at centre-forward!"