Ronnie O'Sullivan joined Judd Trump in suffering a surprise defeat at the English Open on Thursday, while Tom Ford bagged another 147 break.
Trump was beaten at the last-32 stage by Lee Walker earlier in the day, a veteran who now spends much of his time coaching, but the world champion was never ahead in the match despite a pair of centuries.
O'Sullivan, on the other hand, was 3-2 up on an opponent who had never before made the quarter-finals of a significant event such as this one despite being ten years a professional.
And yet the 37-year-old demonstrated an excellent temperament when presented with his chance in the decider after O'Sullivan missed from range, and while he needed two bites of the cherry he was in the end a convincing winner.
"He’s a hardened match player. He played well tonight and he deserves his victory," said O’Sullivan, who will join Eurosport’s punditry team for the rest of the event. "I missed a few balls but I didn’t do too much wrong. There are no excuses and the better man won.
"I think the China events are the biggest tournaments and if you can win one or two of them your season’s sorted. I’m looking forward to going out there and giving it what I’ve got."
With Neil Robertson, Jack Lisowski and Kyren Wilson also having departed earlier, it was a day of upsets in Crawley - none as big as that of Wen, who now goes on to face Mark Selby for a semi-final place.
Selby was a 4-1 winner against Xiao Guodong, breaks of 72, 60 and 50 the ideal response to a century break from Xiao in frame two.
The former world champion has beaten Wen on both occasions they've met previously, though having gone the distance in last year's European Masters - and on the back of this display - he'll know not to take the Chinese lightly.
Teen dream ended but maximum man remains
As O'Sullivan departed, so too did 17-year-old Si Jiahui, who prior to the English Open had not yet won a single game as a professional.
That all changed as he advanced through the rounds here, dispatching Zhou Yuelong 4-0 on Thursday morning, but he was on the receiving end of similar treatment from Tian Pengfei in the evening.
Tian signed off with a 124 break in frame four and will face Ford in the quarters after the Leicester cueman put Shaun Murphy in the shade with a 4-3 victory sealed in remarkable fashion.
Ford responded to being pegged back at 3-3 with a match-winning maximum break, his second of the season - in fact he has been responsible for the only two made so far on the circuit.
Always considered a bright talent, Ford is at last threatening to deliver and on this form will have eyes on a second ranking final, three years after he suffered defeat to Selby in the Paul Hunter Classic.
Ford has now made five maximum breaks in his career, which puts him fifth on the all-time list alongside Murphy and Stuart Bingham.
"Even from the first red, I knew if I missed anything the balls would be open," said Ford. "All I wanted to do was go up for the blue!
"Once I passed 80 I knew that was the match won, and I just had to really concentrate on trying to get the maximum."
Ford will get nothing for the 147 itself - apart from the tournament's £5,000 high break prize - but should there be 20 in the season, World Snooker chief Barry Hearn has promised a £1,000,000 pot to split between all those who have made one.
The record in a season so far is 13, and Ford will need others to contribute if he's to receive a bonus for his second stunning break of the campaign.
An expected thriller between Mark Allen and Barry Hawkins failed to materialise, as the former won 4-0 against an opponent who was far from his best.
Hawkins scored just 37 points as breaks of 60, 89, 100 and 129 saw Allen extend his impressive week, one in which only James Wattana has managed to take two frames against him.
"That's the closest control I've had (over the white) all week," said Allen. "It's been a bad night for Barry, but he's beat me many times in the past and he'll beat me many times in the future."
Allen’s next opponent will be Lee Walker, who held off Gary Wilson to win 4-3 and cap a fine day which began with victory over Trump.
Finally, Ricky Walden beat Thepchaiya Un-Nooh 4-2 and goes on to face David Gilbert, who looks to have an excellent chance to win his first ranking title after a 4-3 victory over Zhao Xintong.
Thursday October 17
Third round - best of 7 frames
TV Coverage: Eurosport
- Si Jiahui 4-0 Zhou Yuelong
- Tian Pengfei 4-2 Dominic Dale
- Tom Ford 4-2 Kyren Wilson
- David Gilbert 4-2 Kurt Maflin
- Ricky Walden 4-3 Michael Holt
- Xiao Guodong 4-3 Jack Lisowski
- Matthew Selt 2-4 Mark Selby
- Fan Zhengyi 0-4 Shaun Murphy
- Graeme Dott 2-4 Thepchaiya Un-Nooh
- Ronnie O'Sullivan 4-1 Hossein Vafaei
- Mei Xi Wen 4-1 Elliot Slessor
- Mark Allen 4-1 Louis Heathcote
- Barry Hawkins 4-2 Fergal O'Brien
- Gary Wilson 4-3 Joe Perry
- Neil Robertson 0-4 Zhao Xintong
- Lee Walker 4-2 Judd Trump
Evening session - fourth round
- Si Jiahui 0-4 Tian Pengfei
- Tom Ford 4-3 Shaun Murphy
- Zhao Xintong 3-4 David Gilbert
- Thepchaiya Un-Nooh 2-4 Ricky Walden
- Ronnie O'Sullivan 3-4 Mei Xi Wen
- Xiao Guodong 1-4 Mark Selby
- Mark Allen 4-0 Barry Hawkins
- Gary Wilson 3-4 Lee Walker
Watch the English Open live on Eurosport and Eurosport Player, with studio analysis from Ronnie O’Sullivan and Jimmy White