Robertson, who was also crowned UK Champion in 2013 and 2015, eventually proved a too strong for China’s Pang, who was making his bow in a quarter-final of one of snooker’s Triple Crown events.
While Pang took the opener, he made a number of unforced errors and rarely put Robertson under pressure early on.
The 26-time ranking event winner made just one break over 50 as he reeled off the next four frames and then constructed a superb run of 111 to move within the cusp of victory.
Yet the momentum shifted in a remarkable seventh frame, when 25-year-old Pang came to the table 72-11 points down with only 51 on offer.
Instead of shaking hands, he got a snooker and when Robertson fouled and gave up seven points by hitting the black, there was also the bonus of a free ball which gave him the impetus to make an outstanding clearance of 51 to pinch the frame.
“That is the thing that would be on a quiz of what happened next,” said Robertson.
“You could never even try to do that again. I was brilliant to get to 5-1. That would be one of the breaks of the tournament [from Pang].”
Seemingly with a new found freedom, qualifier Pang crafted a wonderful 115 break and then won the ninth frame.
However, his comeback ended there, with Robertson rounding off the match with a break of 75.