In a high-quality encounter between two of the most aggressive operators on the tour, neither player took a backward step and Maguire needed to produce breaks of 90 and 133 to win the last two frames and prevail 5-4.
Maguire looked sharp all afternoon and after Murphy had dictated terms in the opening frame, the Scot eased into his work with breaks of 105 and 84 to lead 2-2 before Murphy levelled the scores thanks to a nerveless clearance that allowed him to steal frame four.
Maguire dominated the fifth frame to inch back in front but Murphy appeared to take control of the match when putting together runs of 81 and 58 to move within a frame of victory.
However, last season's Tour Championship hero would not be bowed and after compiling a classy hand of 90 to force a deciding frame, Maguire duly booked his place in the last four with a brilliant total clearance that ended Murphy's title defence with a bang.
Maguire said afterwards: "I enjoyed it. When I broke off at 4-4, I left the usual red that you leave and his long potting is awesome - I thought 'I actually fancy him potting this and making a break' and I would have shook his hand and said 'listen, well played' because I enjoyed it from start to finish.
"We were geeing each other up. When he made a frame-winning break, I was coming back at him and then he was coming back at me. That's the first game I've enjoyed in a long time.
"The break to go 4-4, I was delighted with that because I went for a die-or-die - I had nowhere to go with a nasty cut on the red which I just thought 'if it doesn't go in, that's it' and I never put a foot wrong after that. In amongst them all week, I've scored well. It's just getting in."
There was a dramatic conclusion to the match on the second table as Jordan Brown pulled off the biggest win of his career to date when holding off Mark Selby.
Breaks of 105, 55, 63, 52 and 53 allowed Brown to dominate much of the contest but he couldn't quite shake Selby off, the latter steeling himself to take the match into a deciding frame.
Even then, Brown made the early running until Selby clawed his way back into the ninth frame and then looked likely to steal it when laying a tricky snooker on the blue, which Brown couldn't escape from, to leave himself the final three colours for victory.
However, as Brown cut a despondent figure in his chair, Selby failed to land on the black before later missing to middle when victory had again looked assured. This time Brown made no mistake, crunching the black into the corner pocket before punching his fist in delight.
As the drama was unfolding on the table, there was to be a significant twist off it as Carter pulled out of his eagerly-anticipated showdown with old foe O'Sullivan due to health reasons. O'Sullivan now receives a bye to the semi-finals where he will face Mark Williams, who edged Tom Ford 5-4.
