It was a brilliant contest in Leicester, with O’Sullivan taking a 2-0 lead thanks to breaks of 67 and 107, only for Zhou to respond with a 78 and a 102.
The Rocket went back into the lead, but Zhou forced a decider thanks to a break of 65 and was within a whisker of a first win over the world number one.
The Jumping Dragon got in first in the final frame thanks to a superb long red, but quickly lost position, missed his next red and the Rocket stepped in, making 90 to win the match.
The victory continues the incredible run of form for the 48-year-old after winning the UK Championship last month and the Masters just last week.
Only two players have beaten the Rocket all season – Zhang Anda (twice) and Lyu Haotian – and next up to try and beat the GOAT will be Gary Wilson in the last eight.
‘Zhou Yuelong had 96 per cent live pot success,’ Stephen Hendry said on ITV4. ‘If that’s not going to work, I don’t know what is against Ronnie O’Sullivan.’
O’Sullivan said of Zhou: ‘I think he’s really improved a lot as a player. Hit’s the ball a lot firmer in the balls, safety is better, composure has improved, he’s really improved massively in all areas.’
However, on his own game he added: ‘I don’t know, mate. I just can’t fathom it out. I’ve got to really consider whether I can carry on feeling how I’m feeling out there, I just don’t get any enjoyment the way I’m hitting the balls, I feel like it’s hard work
‘I ain’t got a clue where the balls are going, a lot of it is guess work.’
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