British number one Dan Evans produced a superb fightback to beat third seed Karen Khachanov 3-6 7-6 (9-7) 6-4 and reach the European Open semi-finals.
Evans, 30, faced match point in the second set but went on to take the tie-break after a hotly disputed line call.
Early in the deciding set he broke Russian world number 17 Khachanov, before completing victory in two hours 40 minutes.
Evans will face Frenchman Ugo Humbert in the last four in Antwerp.
Leading by a set and a break of serve up, Khachanov was outraged after an Evans forehand was not called out, which gave Evans a set point in a tense tie-break.