Ding Junhui edged past Mark Williams 6-5 in a final-frame decider to move into the quarter finals of the Masters at Alexandra Palace.

While neither player was at their best in a fragmented opening in which the first two frames were shared with a top break of 36, an absorbing contest sparked into life after the mid-session interval.

Having made breaks of 57 and 70, Wales’ two-time winner Williams led 3-2 before the momentum swung back towards his Chinese opponent, who enjoyed runs of 64 and 60.

In a see-saw encounter Williams compiled a sublime break of 136 to level and then pinched the ninth frame after Ding faltered on 66 to lead 5-4.

However, the 2011 champion made a 76 to force an 11th frame after enjoying a fortuitous run of the balls, and then sealed his victory with a wonderful break of 90.

“I had a bit of luck at 5-4 down. I smashed all the balls and he got no chance,” Ding told BBC Sport.

“I love the Masters tournaments. They are always tough. We both struggled at the start and I told myself to relax.”

Ding, will now face Judd Trump or Barry Hawkins in the last eight, while Mark Selby plays Ali Carter later on Monday (19:00 GMT).