The world number one was 9-1 up against Kim Huybrechts. But the Belgian then won five legs on the spin before van Gerwen closed out a
9-6 win. Afterwards, the three-time and defending
Masters champion expressed his annoyance.
"Winning is the most important thing but I'm not totally happy. I started thinking about tomorrow and that's the biggest mistake you can make - I knew I was going to win and I switched off," he said.
"I didn't make a lot of mistakes, but who cares how you win, as long as you win. After I was 9-1 up I played poorly but a win is a win and I can't complain."
The Dutchman takes on James Wade in Sunday's quarter-final. Gerwyn Price or Gary Anderson would be his semi-final opponent, should he beat the Machine. A fourth straight Masters title is the target for van Gerwen.
"It's about what happens in the future and you always have to be hungry for more, and I feel comfortable for this year. I'm going to make it four in a row. I know I'm good enough and I want to win this," he said.
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