Robertson was trailing 3-1 when he called it a day, having suffered from flu-like symptoms” during the match.
Elsewhere, defending champion Mark Selby and world No.1 Judd Trump both continued their progress in China.
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Three-time world champion Selby rattled off breaks of 58, 60, 79 and 122 on his way to victory against 32 seed Martin Gould.
The Jester from Leicester recovered from losing the first frame to take a 4-1 lead and rounded off proceedings with a 122 after 38-year-old Gould had cut the arrears with an 83.
Trump had rather less trouble than Selby, defeating Zhou Yuelong 5-0, with runs of 69, 121, 69 and 51 - the victory means the world champion is yet to drop a frame at the event in Guangzhou.
Stephen Maguire and Jordan Brown lost tight encounters 5-3 to Joe Perry and Kurt Maflin respectively.
Luca Brecel's run continued with a convincing 5-0 win over Mark Joyce, while Barry Hawkins trounced Mitchell Mann 5-1.
David Gilbert recorded a routine 5-2 win over Matthew Stevens.
Meanwhile, there were wins for Noppon Saengkham, Anthony McGill, Chris Wakelin, Hossein Vafael, Zhao Xintong and Shaun Murphy – with Mark Allen and Kyren Wilson among the big names to crash out.

CHINA CHAMPIONSHIP ROUND TWO

Noppon Saengkham 5-4 Mark Allen
Anthony McGill 5-3 Jack Lisowski
Chris Wakelin 5-2 Yan Bingtao
Hossein Vafael 5-3 Kyren Wilson
Zhao Xintong 5-3 Xiao Guodong
Shaun Murphy 5-3 Ryan Day
Matthew Selt 5-1 Neil Robertson (retired ill at at 3-1 down)
John Higgins 5 – 3 Li Hang
Kurt Maflin 5 – 3 Jordan Brown
Mark Selby 5 - 2 Martin Gould
Joe Perry 5 – 3 Stephen Maguire
David B Gilbert 5 – 2 Matthew Stevens
Luca Brecel 5 – 0 Mark Joyce
Barry Hawkins 5 – 1 Mitchell Mann
Judd Trump 5 – 0 Zhou Yuelong
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