Anthony Sinisuka Ginting proved to be the former world champion's stumbling block again, as Indonesia's top men's shuttler took the quarter-final tie comfortably, winning 21-13, 21-14 in 36 minutes in Saarbrucken, Germany.
Ginting, ranked world No.6, led for nearly the entirety of the match, stopping Loh from mounting any semblance of a comeback, and then scoring seven points in a row in the second game to turn a 9-8 edge to a 16-8 lead to close out the match.
He advanced to face India's Kidambi Srikanth in the semi-finals. In the other semi-final tie, Taiwan's world No.4 Chou Tien-chen will meet France's Tomo Junior Popov.
This is the third consecutive tournament in as many weeks in which Loh - the world No.5 - has made the quarter-finals, following similar feats at the Denmark Open - where he upset world No.1 Viktor Axelsen - and the French Open.
Loh had won last year's Hylo Open, sparking a superb run of form which culminated in his extraordinary BWF World Championship triumph in Huelva in December.
He is next slated to play in the Australian Open in Sydney from 15 to 20 November.
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