Wilfried Bony's late header secured a 2-1 victory at Old Trafford on Sunday to leave Swansea with a trip to either Crawley, Bristol Rovers or Birmingham in the fourth round.
Michael Laudrup's side won the Capital One Cup last season, knocking out Chelsea in the semi-finals, and De Guzman fancies another final date at Wembley.
"We will be ready for the next round," said De Guzman. "If we can beat Manchester United, we can beat anyone.
"We have had a taste of Wembley and we are kind of getting used to it. It would be great to get there in another competition."
United have been struggling at home in recent weeks and De Guzman acknowledged the negativity at Old Trafford helped to spur Swansea to success.
"You could tell their fans weren't pleased when they played the ball backwards and we used that to our advantage," said the 26-year-old.
"You could feel it (edginess in the stadium). The fans wanted to win.
"They are at home. Their crowd is an extra man. But if they are turning their backs or things are not going well and the team is not playing the way they should, as an opposition player you have to use that.
"You could hear the fans booing at the end of the game and when they played the ball backwards we knew that as well."