O'Sullivan held a 6-2 advantage following an error-strewn afternoon session, but he and Wilson continued to struggle at the table in the evening. 2010 world champion Neil Robertson, watching from home, even offered up an excuse for the players, saying it was the 'worst he's ever seen a one table set up play," blaming an unsuitable cloth in humid conditions.
Yet O'Sullivan managed to extend his lead to six frames. Wilson threw away a 53-point lead in the first frame of the session and then gifted the second to O'Sullivan too after missing an easy black.
But the Warrior finally came to life to kick off a remarkable comeback. He pulled one frame back with a run of 92 before reducing the deficit to four once more after winning another marathon frame littered with errors.
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Wilson made it three in a row after the break, playing by far the better snooker as a lacklustre O'Sullivan struggled to stay at the table for more than a minute. A run of 58 then helped the underdog to go within two.
Now just 8-6 up, O'Sullivan finally found some form to take a closely-fought frame and bring Wilson's run of four consecutive frames to an end.
Unfazed, Wilson responded with a fantastic century, but O'Sullivan took the last frame of the session after Wilson missed a crucial, frame-ball red.
Kyren Wilson knocks in vital century against Ronnie O'Sullivan
After falling six behind, Wilson will be delighted to remain within touching distance heading into the final day.
What drama! Kyren Wilson misses crucial red and Ronnie O'Sullivan cleans up
First session report
Five-time champion O'Sullivan took a quick first frame but Wilson showed guts to level despite falling 44 behind, grinding his way through a tough second frame to get on the scoreboard.
But the underdog slipped in the third to let O'Sullivan in, who made no mistake to make it 2-1 before doubling that lead with a break of 75 before the mid-session interval.
Ronnie O'Sullivan lands outrageous fluke in final
Neither player was anywhere near their best as the afternoon session continued as they struggled o build big breaks while making a series of elementary errors.
The Rocket then fluffed an easy safety to let Wilson pull one back for 3-2 with a break of 63, but the low standard of play suited the Rocket who was able to steal frames whenever Wilson made mistakes at the table.
He regained a two-frame lead in the sixth after Wilson missed an easy red, and then hit the first century of the match to go 5-2 up.
Ronnie O'Sullivan with brilliant century - 'the crowd are loving every moment of this'
O'Sullivan then made a litany of errors in a marathon eighth frame and was visibly shocked at his own performance, but nerves got the better of Wilson who failed to capitalise and the Rocket took the scrappiest of frames to make it 6-2 ahead of the evening session.
THE BREAK PODCAST
Ronnie O'Sullivan may have a three frame lead over Kyren Wilson going into the last day of the World Snooker Championship final, but as ex player Neal Foulds and commentator Philip Studd discuss with Rachel Casey, this is a very unpredictable year and an extraordinary Championship; anything could happen.
The trio have a comprehensive review of the first two sessions of the final and look ahead to the next two.
Plus Rachel has a lively conversation with Eurosport Presenter Colin Murray on his three week experience at the Crucible being in the company of Jimmy White and all the top competitors.