World number one Mark Selby has suffered a shock BetVictor Welsh Open defeat to rising 19-year-old Belgian star Luca Brecel.
Brecel, who became the youngest player to compete in the Crucible stages of the world championships in 2012, came from 2-0 and 3-2 down to record a 4-3 last-16 win over Selby, ranked 65 places above him.
Although Selby knocked in breaks of 131 and 114, Brecel levelled the game at 3-3 with a 101 of his own before capitalising on a mistake in the decider by the former world champion to set up a last-eight clash with Stuart Bingham or Ricky Walden.
It means the top three seeds are now all out after Ding Junhui lost in the first round and reigning world champion Ronnie O'Sullivan exited in the third.
Following his win at the Motorpoint Arena in Cardiff a delighted Brecel told World Snooker: "I think I showed a lot of bottle and I'm very satisfied because the hard work is paying off now.
"That was my best performance at this level because I was 2-0 down against the world number one. This could help me a lot in the future.
"For the last two years I haven't worked hard enough, so now I am working very hard on the mental side and practice."
Four-time world champion John Higgins, who is without a ranking title since the 2012 Shanghai Masters, came from 2-1 down to beat Michael Georgiou 4-2.
Higgins said: "I feel as if I'm close to playing well, I'm just trying to get to the business end of tournaments and give myself confidence.
"I'm slowly getting there and maybe it will be this week. I've not been to the later stages for two or three years."
World number six Judd Trump is also out following a 4-1 defeat by home favourite Mark Williams, who was rarely troubled.