The Brum, winners of the 2011 cup, made the most of their chances to overcome their Premier League opponents who won this competition last season and the result was a thing of delight for an excited Clark.
"I'm absolutely delighted," Clark told Sky Sports.
"I think to win a game like that against the quality of opposition we're up against is very satisfying.
"Not only are Swansea the holders but I said before the game that I felt it was the hardest tie we could have got outside the so-called top six, a club that's on the up in everything that they do.
"Even though they made changes I don't think it affects them as they've got a philosophy that runs through the club."
Clark added: "I hope the players gain confidence from the victory.
"I can see the players are gaining confidence game-by-game, there were some terrific individual performances out there."