Jordan Brown lost 6-0 to John Higgins in the first round of the Players Championship, three days after winning a first ranking tournament.
Northern Irishman Brown lifted the Welsh Open title on Sunday but was not given a chance by Scotland's Higgins.
The four-time world champion made a century break in each of the first three frames of a comfortable win.
Higgins will face Mark Selby in the last eight following his 6-4 victory over Welshman Mark Williams.
Williams led 2-0 and 4-3 in the match but Selby took the final three frames with consecutive breaks of 78, 73 and 64.
Elsewhere on Wednesday, Barry Hawkins advanced to the semi-finals with a 6-2 win against Stuart Bingham.
Hawkins rallied to claim five unanswered frames after Bingham had taken a 2-1 lead, and will play either Ronnie O'Sullivan or Jack Lisowski for a place in the final.
Brown, a 750-1 outsider, beat O'Sullivan 9-8 in the Welsh Open final on Sunday to become the lowest-ranked winner of a ranking event since 1983.
But he was heavily beaten in his first outing since that victory, as Higgins hit 122, 133 and 121 during an emphatic start to the match in Milton Keynes.
The Scot was on course to become the first player in history to hit four opening centuries on two different occasions, having achieved the feat against O'Sullivan in 2005.
However, a bad position after potting a red meant his fourth-round break stalled at 57, but he still went into the interval 4-0 ahead.
Brown got into the match for the first time in frame five but a poor miss on the pink while 58-49 up saw him sacrifice the frame, with Higgins take the sixth frame comfortably.
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