Zhao led 9-7 after Saturday’s action before Ding reduced the deficit to a single frame by taking the opener on Sunday.
The 29-year-old, looking to become the first first-time winner to retain the world title at Sheffield’s Crucible Theatre, quickly snuffed out any danger to his title defence.
Ding was the first Chinese player to win a ranking event, but Zhao capitalised on a series of mistakes by his compatriot to pull away.
A break of 108 in the penultimate frame helped seal a last eight clash with former world champion Shaun Murphy.
“Today I think there was more pressure,” Zhao told BBC Sport. “I know Ding didn’t play very well in the last session but the pressure is very big.
“This year I just don’t want to lose any match so it feels very different.”
The clash was expected to draw a big television audience in China and Zhao admitted he felt the tension of playing in such a high-profile match.
“This was a very special match for us that everybody knows about and wants to keep eyes on it. It was very different last year when I was a nobody guy,” he said.
Ding, the 2016 runner-up at the World Championship, added: “It was not good enough. I was a little bit disappointed in the first two sessions.
“It’s hard when I’m 7-9 down and he found his game quickly. I tried, it was just not working.”
World number one Judd Trump moved closer to booking his place in the quarter-finals after building a 9-7 lead against Iran’s Hossein Vafaei. (AFP)
