Regarded by many as snooker’s greatest ever player, Englishman O’Sullivan now lives in Dubai with his family and is selective about the events he plays in.
He had beaten 27-year-old Zhou in each of their previous seven meetings, but this result continued a great competition for China, with seven players from the country reaching the last 16.
Immediately after the match, O’Sullivan was asked if he would be playing in next month’s Masters in London. That event starts on 11 January, with the draw taking place this Sunday.
O’Sullivan, who continues to play a number of events in Asia and the Middle East, said: “I don’t know, I’ve not made any decision – I will have to wait and see. I will have a nice Christmas and see how I feel in January.
“I still get disappointed if I lose if I play well and I probably wasn’t the better player on the day. I did my best. Life is quite good, I’m just trying to enjoy working.
“I’ve enjoyed playing since the start of the season and feel I’m hitting the ball all right.”
O’Sullivan’s birthday coincides with this tournament’s quarter-finals. He says he will still watch the snooker on TV, as well as “going for a run and eating some nice food”.
Three-time world champion Mark Williams feels the only way O’Sullivan will get back to winning ways is by playing more often.
Williams, who like O’Sullivan and John Higgins is part of snooker’s fabled Class of 92, said on BBC Two: “The reason he is not winning as many tournaments as he has is he is not playing enough. For him to get back to winning consistently he has to play more, but when you are 50 it is hard to play in all the tournaments.
“His motivation is just winning. He loves to win the big events, and even though he has said he doesn’t want to overtake Stephen Hendry’s record at the World Championship [both Hendry and O’Sullivan are on seven titles], I think that’s his main aim.”
Six-time UK and world champion Steve Davis reached the quarter-finals of the World Championship aged 52 in 2010.
He agrees O’Sullivan cannot expect to be successful if he plays a part-time tour schedule.
Speaking on BBC Four, Davis said: “It is going to be problematic going forward for Ronnie O’Sullivan if he does not commit to the whole circuit.
“He has been playing the game so long, so it’s his choice how many tournaments he plays a year. But the standard is better now and it’s going to be tough for him if he doesn’t fully commit, so he’s at a bit of a crossroads.
“He still puts in great performances, but the problem is there are so many other players putting in fantastic performances as well.”