Ding booked his place in the semi-finals, where he will meet defending champion Mark Selby in a repeat of last year's final, thanks to a thrilling 13-10 victory.
However much of the talk after the match surrounded O'Sullivan and a missed opportunity to score a 147, when he opted to take a pink from the 13th red when a maximum looked a formality.
It has been suggested O'Sullivan spurned the opportunity of a 147 due to the low prize money on offer, just £15,000 compared to £165,000 when he scored a maximum in a record five minutes and 20 seconds.
However O'Sullivan denied such claims when saying after the match: "I was playing for the black but I just didn't get on it.
"I don't take this stuff too seriously. I like to entertain, I like to put on a good show, and I like to have fun and I like to enjoy myself. In a world where everything's so serious, I like to make it fun."