“The Rocket”, as the Englishman is called O’Sullivan, clearly leads to his compatriot Judd Trump after two of a maximum of four sessions.
The player, who first won 18 frames, follows England’s Mark Selby as a world champion.
For O’Sullivan, it’s about the seventh World Cup title with which he could catch up with Scots Stephen Hendry.
In theory, O’Sullivan could bring about the decision on Monday afternoon (2 p.m./Eurosport).
The fourth session would start in the evening (8 p.m.).