The 30-year-old's resounding 9-4 success in Milton Keynes was a seventh in succession against four-time Crucible champion Higgins.
Trump admits matches against the 45-year-old no longer hold a fear factor and felt his experienced opponent "hadn't been practising that hard."
"I used to think I was playing well against him and always get a good lead but he would always find something from somewhere," said Trump.
"But the last few times when the big clearances have come up he hasn't cleared up in the same way that he used to.
"I don't think he's playing to the same level that he used to play, even the last couple of times I've not played great and still managed to beat him.
"It's sort of like I'm on the way up and he's kind of on the way down, with his age as well, he's been around so long.
"He's still a tough player to beat (but) I certainly feel a lot more confident playing against him now and I really fancy my chances.
"I felt comfortable. He wasn't really playing well enough to finish the games in one chance. He obviously hadn't been practising that hard, I don't think."
Trump, who beat Higgins 18-9 to lift the world title in Sheffield last year, took control of the match from the outset and led throughout.
After losing four of the opening five frames, Higgins, ranked fourth in the world, briefly clawed his way back into contention at 4-3.
World number one Trump quickly reasserted his superiority by winning the next four in a row, including producing a superb break of 135 in frame 11, before going on to clinch his place in the semi-finals.
He will face Higgins' practice partner Stephen Maguire on Wednesday in the last four of the eight-player rankings event.