Van Barneveld - a Grand Slam winner in 2012 - rolled back the years to defeat reigning champion Gerwyn Price in a deciding-leg thriller in their second Group A contest.
The veteran stole the headlines with a vintage display at the Aldersley Leisure Village, defying a 106 average from Price to prevail in an epic, despite trailing 3-1 and 4-3 during the contest.
Price made a blistering start, but Van Barneveld came roaring back, registering legs of 11, 14 and 14 darts to force a decider, before sealing his progression to the last 16 with a nerveless 67 finish on double 16.
"This is one of the best wins of my career," insisted Van Barneveld, who will take on World Youth Champion Ted Evetts in his final Group A tie on Monday evening.
"Gerwyn was a great sport. I think he was enjoying the game, and I was enjoying the way he was playing. This is what darts is all about, and I'm over the moon with this result."
Price will now take on Chisnall in a winner-takes-all clash on Monday, after the 2014 runner-up opened his Group A account with a 5-2 win over Evetts, averaging 101 and landing four 180s in the process.
Meanwhile, three-time Grand Slam winner Van Gerwen has already sealed his spot in the knockout stages, breezing past Luke Woodhouse 5-1 with a 99 average and 50% on the doubles to cap off a dominant display.
The Dutchman will face European Champion Ross Smith in a blockbuster Group G clash on Tuesday, after Smith recorded a 5-2 win over Nathan Rafferty to claim his first win on the Grand Slam stage.
Dirk van Duijvenbode was the first player to secure a place in the last 16 on Sunday afternoon, reeling off four straight legs from 3-1 adrift to defeat Rob Cross, with a ten-darter in leg five sparking his comeback.
Cross now faces a straight shoot-out for Group D qualification against Martin Schindler, after the German won the final three legs of his clash against Adam Gawlas, who is unable to qualify following Van Duijvenbode's victory.
Welsh ace Clayton is yet to drop a leg in this year's Grand Slam, making it back-to-back whitewash wins in Wolverhampton after sweeping aside Jermaine Wattimena to guarantee top spot in Group F.
"I know I'm not firing on all cylinders, but I think I'm getting back to my level. I'd love to win this, and I'm hunting this title," declared the former Premier League champion.
2022 Cazoo Grand Slam of Darts, Sunday November 13, afternoon Session, Groups A-D:
- Ritchie Edhouse 5-2 Lisa Ashton (C)
- Martin Schindler 5-3 Adam Gawlas (D)
- Mensur Suljovic 5-2 Christian Perez (B)
- Dave Chisnall 5-2 Ted Evetts (A)
- Danny Noppert 5-2 Simon Whitlock (B)
- Dirk van Duijvenbode 5-3 Rob Cross (D)
- Raymond van Barneveld 5-4 Gerwyn Price (A)
- Michael Smith 5-1 Joe Cullen (C)
Clayton now plays World Cup winner Damon Heta in a stellar tie on Tuesday night, after the Australian fought back from 4-1 down to edge out America's Leonard Gates in a remarkable contest.
Gates gifted the Australian a reprieve with a miscount in the penultimate leg before spurning three match darts in the decider, leaving Heta, Wattimena and Gates to battle it out for second spot.
Luke Humphries is the fifth player assured of his place in the last 16, producing the performance of the tournament so far to dispatch Ryan Searle 5-1 with a sensational 107 average.
Sixth seed Humphries crashed in four 180s and converted five of his nine attempts at double to make it two wins from two in Group G, leaving Josh Rock, Searle and Scott Williams to scrap it out on Tuesday.
Earlier in the night, Rock secured his first Grand Slam victory with a deciding-leg win over Williams, hitting four 180s, taking out a 145 finish and firing in a 13-dart hold to claim a precious two points.
Elsewhere, World Champion Peter Wright remains top of Group E, coming through a dramatic all-Scottish affair against Alan Soutar, who squandered six darts for victory in a dramatic finale.
- Groups E-H Second Matches
- Josh Rock 5-4 Scott Williams (H)
- Damon Heta 5-4 Leonard Gates (F)
- Ross Smith 5-2 Nathan Rafferty (G)
- Nathan Aspinall 5-1 Fallon Sherrock (E)
- Jonny Clayton 5-0 Jermaine Wattimena (F)
- Michael van Gerwen 5-1 Luke Woodhouse (G)
- Peter Wright 5-4 Alan Soutar (E)
- Luke Humphries 5-1 Ryan Searle (H)
Wright will lock horns with Nathan Aspinall in their final Group E clash on Tuesday, after the World Grand Prix runner-up got his Group E campaign back on track with a 5-1 success against Fallon Sherrock.
"I had to come back tonight with a big result, and playing Fallon is never easy," reflected Aspinall, who averaged 94 and won five consecutive legs to end Sherrock's hopes of qualification.
"It's just not clicking for me at the moment, but hopefully I can have a big performance against Peter on Tuesday, which is going to be a do or die game."
Michael Smith extended his remarkable winning run in the Grand Slam's Group Stage to 15 games with a comprehensive 5-1 win over Joe Cullen to take control of Group C.
"This is one of my favourite tournaments. I have won two games and I'm still not through, but that's the beauty of this event," said the St Helens star, who took out 114 and 78 to complete the job.
Smith's final round-robin fixture will see him play Ritchie Edhouse, who preserved his qualification hopes with a convincing 5-2 win against Lisa Ashton to draw level with Cullen in the table.
Monday November 14 (1900 GMT)
- Groups A-D Third Matches
- Dirk van Duijvenbode v Adam Gawlas
- Raymond van Barneveld v Ted Evetts
- Simon Whitlock v Christian Perez
- Danny Noppert v Mensur Suljovic
- Gerwyn Price v Dave Chisnall
- Joe Cullen v Lisa Ashton
- Michael Smith v Ritchie Edhouse
- Rob Cross v Martin Schindler
Danny Noppert turned on the style in his 5-2 win over Simon Whitlock to maintain his 100% record in Group B, averaging 99 to move to the brink of a place in the knockout stages.
The UK Open champion now takes on 2018 semi-finalist Mensur Suljovic in his final round-robin tie, after the Austrian battled past PDC Asian Champion Christian Perez to move level on points with Whitlock.
Groups A-D draw to a close on Monday evening, before players from Groups E-H continue their battle for qualification on Tuesday.
The top two players from each group will progress to the knockout stages, with the last 16 action beginning on Wednesday November 16.
Tuesday November 15 (1900 GMT)
- Group E-H Third Matches
- Schedule TBC