China's Ding Junhui dropped a 5-3 lead to lose to defending champion Neil Robertson 6-5 in the opening match of the Masters at Alexandra Palace on Sunday.

Australia's Robertson played flawless snooker in the last three frames to reach the quarterfinals. He will face Mark Allen or Mark Davis.

Robertson started the match strongly with a break of 76 to win the opening frame, and he added a scrappy second for 2-0. Ding, who won this event two years ago, stormed back to take five of the next six frames with top runs of 103, 53, 127 and 54.

A break of 100 from Robertson in frame nine kept him in contention, then the key moment of the match came in the tenth when Ding, on a break of 50, was unlucky not to land on a red when splitting the pack off the blue. Robertson blasted in a trademark long red and crafted a superb 62 clearance for 5-5.

And when Ding left his opponent a red to a center pocket while breaking off in the decider, Robertson capitalised brilliantly with a run of 90 to secure victory.

"I did think I was out," said the 30-year-old. "He was a bit unlucky, if he had landed on a red in the 10th frame it was all over.

"Overall I thought it was a great match. Two champions, some big breaks and close frames. I was really pleased with the way I cleared up to go 5-5. Overall if you were to tell me I could play like that for the rest of the tournament I'd be very happy.

Ding said: "I played well today. I think 5-3 means nothing because he was 3-2 up then. I won three frames then and he won the last three frames. Anything can happen when he's playing very well. Sometimes you need a little bit of luck. It doesn't matter. He's a top player in the world. I just play. I was happy to play this game today and practise hard, and now I'll just go back to practise looking for the next tournament."