Judd Trump will meet Chris Wakeklin in the last eight, after he pulled off an impressive win against local hero Ding Junhui.
Wakelin said: "I just believe in myself now. The results over the last couple of years have given me the confidence to go into these sorts of situations and have belief that the game is there.
"The biggest thing for me wasn’t the three centuries on the trot, it was the last frame.
"He missed a red in the middle and given what happened before, I came to the table unsure about how I was feeling.
"When I got motoring through the balls I was confident I was going to get over the line.
"Every single player on tour is capable of playing like that, but to do it on the big stage is something that I’ve not been capable of.
"I’ve not had the temperament and the belief to stand there and knock in three centuries on the trot in front of Ding and a home crowd in China.
"That is a massive moment for me and it will give me a lot of confidence going forward."
This will be one of the most anticipated matches of the tournament so far for fans of China, as the two stars (ranked no 11 and no 13 in the world, respectively) come to blows for just the fourth time.
Zhang has had dominated all three of their previous meetings, dropping just three frames, but a lot has changed for Si since their last match at the 2023 Scottish Open.
Si, still just 22, is seen as one of the future stars of the game and he has proved that with a brilliant win at the German Masters and a run to the semi-finals of the Saudi Arabian Masters last month.
Zhang is no slouch, of course, and China's second and third ranked players meeting at this stage will be box office in the Far East.
Shaun Murphy will enter his match with Xiao Guodong as the favourite but he has struggled to get the better of the world No 29 in their limited meetings.
In just five matches between the pair they each have two wins, with one draw, although Murphy did beat Xiao just a month ago in the Saudi Arabian Masters, winning 6-2.
Jack Lisowski was also on fire on Tuesday, whitewashing Wu Yize 5-0 to set up a quarter-final meeting with Long Zehuang - a player he has never faced before.
Lisowski said: "If you are asking me if I can win it, yeah if I play really well I have a chance.
"Just because you have played three or four good games you aren't entitled to do well.
"Everyone is really tough and you just have to keep plugging away.
"I could play garbage, but hopefully I'm here giving another cringe interview after winning!"
While Chris Wakelin sprung an upset on Ding it is likely to be a totally different matter against Judd Trump, who has continued his blistering form in recent weeks and months.
The world No 1 will be feeling confident against Thursday's opponent - given he's beaten him on every previous occasion they've met.
Trump has a perfect 13-0 record against Wakelin and has also won 70 per cent of frames played.
The last met in the Players Championship in February and the time before was in the final of the Northern Ireland Open last October, with The Ace in the Pack taking home the trophy after a dominant 9-3 win.
The world No 22 made three consecutive century breaks against Ding to take a 3-1 lead before a spirited fightback set up a nervy finish.
Wakelin added: "I just believe in myself now. The results over the last couple of years have given me the confidence to go into these sorts of situations and have belief that the game is there.
"The biggest thing for me wasn't the three centuries on the trot, it was the last frame.
"He missed a red in the middle and given what happened before, I came to the table unsure about how I was feeling.
"When I got motoring through the balls I was confident I was going to get over the line.
"Every single player on tour is capable of playing like that, but to do it on the big stage is something that I've not been capable of.
"I've not had the temperament and the belief to stand there and knock in three centuries on the trot in front of Ding and a home crowd in China.
"That is a massive moment for me and it will give me a lot of confidence going forward."