China's He was clearly nervous right from the start. O'Sullivan gave him several chances, but he never got into a rhythm and missed simple balls at times. As a result, O'Sullivan quickly took a 2-0 lead with breaks of 72 and 97.
Although He made more of his chances in the third frame, he made an unusual mistake on green in the final game on the colours when he led the nearby cue ball illegally on the shot - this even resulted in a free ball, which O'Sullivan easily pocketed, including the other colours, to make it 3-0.
He also had a good chance in the fourth frame, but his attempted entry shot not only stayed on the table - he also offered O'Sullivan an open table. He thanked him with a 113 century break and took a 4-0 lead into the break.
O'Sullivan not perfect, but ice-cold
It was the same game after the mid-session interval. O'Sullivan opened with a 44 before making a slight error. He came back with a 42, but then made a mistake and missed a complicated red.
The record world champion then collected a few points, but then also made a mistake. But the Chinese player was unable to capitalise on this opportunity either.
He potted the colours up to and including brown, but left the cue ball on the wrong side of blue. In order to make up for the positional error, he went for blue with a lot of power, which resulted in another mistake. O'Sullivan didn't need to be asked twice and decided the frame over pink.
But He didn't let this get him down. He continued to make avoidable mistakes, but O'Sullivan was also far from his top form and repeatedly missed good opportunities.
With two reds on the table, O'Sullivan missed a pottable ball, which He used to extend his lead to 18 points ahead of the colours and snooker O'Sullivan to yellow. This immediately led to the next chance, with which He closed out his first frame.
O'Sullivan loses two frames in a row
He started the seventh frame with a foul, but O'Sullivan then narrowly missed a red, which was left in the pocket.
With the confidence from his first frame win, He immediately capitalised on his first chance this time and played a 77 break - his first shot of at least 50 points.
However, O'Sullivan restored the five-frame lead at the end of the session. First, he played a 52 before rounding off his performance with an 86. The decision between the two will be made tomorrow at the same time.
Wu ends day quickly
On the next table, the match was over quickly. Lei Peifan went into the afternoon with an 8-1 deficit from the first session. The Chinese player took the first frame of the day after 33 points from compatriot Wu Yize thanks to a 69 break, but then had to concede a 68 break himself.
At 9-2, Lei had a chance, but left the table after 24 points and never came back. Wu played a 116 century break to crown his dominant performance. In the round of 16, Wu will meet the winner of the match between Mark Selby and Jak Jones.
