Mark Williams produced a vintage display to beat defending Masters champion Yan Bingtao 6-4 at Alexandra Palace.
The Welshman's season has been severely hampered since he contracted Covid-19 and was forced forced to miss a number of events, but from 3-1 down he overpowered Yan who was shut out for large periods of the second half of the match.
Yan raced out of the blocks with breaks of 64, 71 and 57 to build a two-frame advantage, marching into the mid-session interval having controlled the early part of the contest.
However, Williams was typically unperturbed and hit straight back with runs of 56 and 62 to level the scores, the fifth frame sealed with a remarkable one-handed pot on the final pink when snookered behind the black.
Yan struggled to keep pace thereafter as Williams continued to turn up the pressure, and further breaks of 67, 64 and 104 made it four frames on the bounce for the 46-year-old who now found himself within a frame of the quarter-finals.
To his credit, Yan kept his title defence alive with a stunning riposte of 122 in the ninth frame, only for a brilliant long red from Williams – who was forced into the pot having just conceded two four-point penalties when preferring to play safe – enough to ensure it was his comeback that would be the match-winning one.
Williams told the BBC: "I've played pretty much like that all season, it's just I've got to a few deciders and had a bit of bad luck.
"Anthony Hamilton had a massive fluke and beat me in the last one, and I had a couple of flukes to win this one – it's just the way it goes. You've got to take them when they come.
"It's such a hard tournament to win when you've got John Higgins, Ronnie O'Sullivan and [Stephen] Hendry about. It's hard to win these tournaments.
"At my age, it's just nice to be in these venues – it's probably the best venue I've ever played in and the whole atmosphere in there was just electric. I'm just going to enjoy it while I'm here.
"In a couple of months I'm 47. I never thought I'd still be getting to these venues, and I've won a couple of tournaments this year as well, which is unbelievable. I'm just enjoying it."
Robertson fights past McGill
2012 champion Neil Robertson came through a tough match with Anthony McGill, eventually prevailing 6-3.
Robertson finished with a flourish by winning three frames in succession to secure his progress to the last eight, but it had been McGill who made the early running.
The Scot led 2-1 and was probably unfortunate not to win each of the opening three frames having potted the final yellow in frame two, only to see the white career round the table and drop into the middle pocket.
McGill spurned another good chance in frame four, allowing Robertson to work his way back into the piece and level the scores at 2-2.
From there on, Robertson slowly began to take control of the contest, claiming a share of the next two frames before turning the screw with breaks of 57 and 62 that helped him secure victory.
“It was tough,” Robertson told Eurosport afterwards. “Probably too much of a break over Christmas for me.
"I only gave myself five good days for practice and certainly felt really, really rusty the first few frames.”