Long Zehuang won the last four frames to stage a stunning fightback and beat four-time World Champion 5-4 at Wuhan Open qualifying in Leicester.
It's the second successive match where Selby has surrendered a significant lead, having led Shaun Murphy 6-2 in the Shanghai Masters semi-finals before losing out 10-8.
The Jester from Leicester fired in runs of 135 and 130 on his way to a 4-1 advantage. However, Long was in superb form to turn the tie around, making breaks of 50, 67, 54 and 67 to take four on the bounce and seal a dramatic 5-4 victory.
Shanghai Masters runner-up Murphy crafted four breaks over 50 in a 5-1 win over returning professional Michael Holt, while Scotland's John Higgins was a 5-1 victor over Belgium's Ben Mertens.
Jimmy White scored a 5-3 win over Dominic Dale to earn his place in the final stages. The Whirlwind made breaks of 62 and 77 as he recovered from 2-1 to to secure the win.