World Grand Prix: Mark Selby loses to Martin Gould in Preston
World champion Mark Selby suffered a shock first-round defeat by world number 18 Martin Gould at the World Grand Prix in Preston.
Gould, who beat Selby on his way to the semi-finals two years ago, came through a tense final frame to win 4-3.
The 35-year-old from Middlesex made a career-high break of 142 in the fourth frame and goes on to face Joe Perry.
Australian Neil Robertson beat Ricky Walden of England 3-2 to set up a last-16 clash with Ronnie O'Sullivan.
O'Sullivan beat Chinese 16-year-old Yan Bingtao on Tuesday.
China's world number five Ding Junhui saw off Yu De Lu 4-2, while England's Anthony Hamilton, winner of last week's German Open, lost 4-0 to Mark Allen of Northern Ireland.
Gould looked on course for a straightforward victory when he led Selby 3-1, and then 3-2 with a 58-0 lead, but the world champion hit back with a brilliant 64 clearance to force a decider.
In a final frame that required a re-rack, following an early stalemate, Selby surprisingly missed two opportunities before Gould took charge with a 54 that proved decisive.