Peter Wright is out of the Boylesports Grand Slam of Darts after suffering a 5-2 defeat to Devon Petersen while Gerwyn Price survived a real scare to progress into the last 16.
The world champion 'only' needed to win three legs against Group E table-topper African Warrior to seal a top-two spot in Group E after Ian White thrashed Dirk van Duijvenbode 5-1 to move level on two points but with a leg difference deficit of two.
However, Snakebite found himself in grave danger at 4-1 down and although he pulled one back, he missed one dart at double 19 for a 155 checkout that would have sneaked him through and Petersen came back to seal his third victory in a row.
Wright averaged a lowly 83 compared to his opponent's mediocre 88 while he missed 13 of his 15 darts at a double in a dreadful performance by most top players' standards.
Meanwhile, White will be amazed to have finished runner-up having started the night almost certain to be eliminated following two defeats out of two with a -5 legs difference.
With little to no pressure, Diamond produced a sparkling average of 108, hit all five of his darts at doubles and sealed the 5-1 win with a 132 checkout to leave van Duijvenbode, who beat Wright on night one, completely shell-shocked.
"I'm happy to top the group," said Petersen. "It was a tough group, we had really good players in there but against me they didn't perform as well as they would hope.
"It wasn't the Peter Wright that we expected but I'm just happy. I feel a lot more comfortable on stage and players are now looking at me as a serious player.
Two-time defending champion Gerwyn Price progressed by the skin of teeth after he came from 4-2 down and survived match darts to defeat Ryan Joyce 5-4.
The Iceman had won his opening two games but his place wasn't guaranteed after Jonny Clayton's 5-0 triumph over Mikuru Suzuki meant his clash with Joyce effectively became winner takes all.
Price had averaged below 90 against both Suzuki and his World Cup-winning team-mate earlier this week but raised his levels to a whopping 106 just at the right time to scrape through with a 100% record - as strange as that sounds.
Despite finishes of 124 and 116, Price found himself 4-2 down as Newcastle's Joyce set up the prospect of a huge upset.
However, the world number three survived one missed match dart from his opponent as he won the game's final three legs without reply to progress to the last 16.
"I was up against it but I never gave up - I dug in deep and I thought I played well today," said Price, who was 4-2 down despite hitting checkouts of 124 and 116. "I bombed a few chances but I knew I had enough in the tank and I think I deserved to win.
"I knew Ryan was going to come and play well and he punished me when I missed a few doubles but I stuck in there until the end. In the last three legs I played well to come back. I could have lost all three games but I'm a little bit more experienced now and maybe that showed."
"I'm so chuffed to get through that," said Clayton. "It wasn't easy but a 5-0 win is brilliant.
"I've been thinking about this game for two days and I wanted to get the win and go through. I've done the job and I'm happy to be in the next round."
Arguably the most miraculous qualification feat of the night was Adam Hunt, who was rock bottom of Group A with a legs difference of minus six ahead of his clash with the highly-fancied Gabriel Clemens.
Having suffered 5-0 and 5-4 defeats to Michael van Gerwen and Joe Cullen in his first two games this week, Hunt then looked almost certainly out for good when trailing 2-0 against the German. But a staggering comeback saw him reel off the next five legs in succession to give him a faint hope of going through.
For that to happen, he needed Van Gerwen to defeat Cullen 5-3 or better and the unexpected pressure certainly took it's toll in the eighth leg of the match.
The Rockstar was losing 4-2 but blasted out of the blocks to leave 93 after just nine darts, with MVG back on 244. However, he missed double 18 on the inside for an 11 darter before accidentally hitting double two when he was trying to leave himself 16 for his next visit.
It didn't look too costly when the Dutchman reduced his score to 169 but three missed darts followed at double seven, with the latter falling inside to leave him awkwardly on seven which he also fluffed and was duly punished.
"It was a different kind of pressure today - I knew I was already through and top of the table, and I was trying maybe too hard, but the most important thing is that I won the game," said Van Gerwen.
"I didn't know the situation with Joe and it was only after the game that I realised he missed. I was focused on myself and I can build on this now.
"I can look forward to the game against Gary Anderson on Saturday night now. Gary is a phenomenal player to play against and lately I've been playing quite well, I hope I can continue the good form."
The other group to be decided was relatively more routine, with Jose De Sousa thrashing Lisa Ashton 5-1 with a 100 average to leave Krzysztof Ratajski needing a victory of 5-3 or better against table-topper Michael Smith to qualify.
The Polish Eagle, however, was no match for Bully Boy's average of 107 which was achieved in spite of missing nine of his 14 darts at doubles.
"The average didn't feel as good as it was because I missed a few doubles but I'm happy," said Smith. "I'm in a decent place at the moment; my mindset is good and my form is good.
"You want to keep the momentum going into the next round and as long as my head's good and my form's good then I'm raring to go."
Smith now faces World Cup team-mate Rob Cross in the second round, and added: "The World Cup was a team game but this is a different matter - it's an individual competition and I want to win it.
"Rob's playing well and it should be a good game. The longer format is good and I feel like I'm in the tournament now. I've got a decent record in this event but I want to push for the title."
Group A
Group B
Group C
Group D
Group E
Group F
Group G
Group H
Scoring System: Each competitor plays each other once in a best-of-nine legs match, with two points going to the winner. The top two from each group will then progress to the knockout stages. Any two-way points tie in any position, the player with best leg difference will finish higher. If two players are still level then the winner of the match between them will progress. There is the potential for a Nine-Dart Shoot-Out should three or more players be tied for points and leg difference. For more details see the format section further down.
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Monday November 16
Afternoon Session (1pm)
TV Coverage: Sky Sports
Group Matches (Best of 9 legs)
Evening Session (7pm)
TV Coverage: Sky Sports
Group Matches A-D (Best of 9 legs)
Tuesday November 17
Afternoon Session (1pm)
TV Coverage: Sky Sports
Group Matches (Best of 9 legs)
Evening Session (7pm)
TV Coverage: Sky Sports
Group Matches (Best of 9 legs)
Wednesday November 18 (3pm)
TV Coverage: Sky Sports
Group Matches (Best of 9 legs)
Thursday November 19 (7pm)
TV Coverage: Sky Sports
Group Matches (Best of 9 legs)
Friday November 20 (7pm)
TV Coverage: Sky Sports
Second Round (Best of 19 legs)
Saturday November 21 (7pm)
TV Coverage: Sky Sports
Second Round (Best of 19 legs)
Sunday November 22
Afternoon Session (1pm)
TV Coverage: Sky Sports
Quarter-finals (Best of 31 legs)
Evening Session (7pm)
TV Coverage: Sky Sports
Quarter-finals (Best of 31 legs)
Monday November 23 (7pm)
TV Coverage: Sky Sports
Semi-finals (Best of 31 legs)
Tuesday November 24
Afternoon Session (6pm)
TV Coverage: Sky Sports
Final (Best of 31 legs)