Nathan Aspinall broke reigning Premier League champion Michael Van Gerwen's impeccable start to his Premier League campaign.
Aspinall beat the world number one 7-5 in Cardiff in only his third Premier League match,
The 28-year-old showed steady nerves to pull ahead after the match was level at 5-5.
"To produce my best performance so far this year against the world number one means a lot," Aspinall said.
"And to get two points and a great win against obviously the best player in the world."
World number three Gerwyn Price was unable kick start his Premier League campaign with a win on home soil.
In his first appearance in Wales since being crowned back-to-back Grand Slam of Darts champion, Price earned his third successive draw in the Premier League against Daryl Gurney.
Price who remains unbeaten, has had to win the last leg to draw in all his League matches this year.
Level at 3-3 Price missed a check out and the chance to go ahead and Gurney took advantage of this on his second attempt at a check out.
"It was a great atmosphere, as it always is in Cardiff and I think that puts that little bit extra pressure on myself to try and perform and win," Price told BBC Sport Wales.
"I tried a little bit too hard today, if I had gone 4-3 up I probably could have won that game."
Price's World Cup of Darts partner and Welsh number two Clayton made his Premier League debut as the third of nine 'Challengers' to star in this year's tournament.
But Clayton was unable to become the first challenger to win a Premier League match as he lost 7-1 to former finalist Michael Smith.
World Champion Peter Wright earned his first Premier League win this season with a 7-5 victory against 2019 runner-up Rob Cross, with Wright throwing a 101 average.
Glen Durrant now tops the table and maintained his unbeaten start in his debut year, with a 7-4 victory against two-time Premier League winner Gary Anderson.
Results: Cardiff, 20 February
Peter Wright 7-5 Rob Cross
Jonny Clayton (challenger) 1-7 Michael Smith
Michael van Gerwen 5-7 Nathan Aspinall
Daryl Gurney 6-6 Gerwyn Price
Glen Durrant 7-4 Gary Anderson
Fixtures: Dublin, 27 February
Glen Durrant v Nathan Aspinall
Rob Cross v Gary Anderson
Daryl Gurney v Michael Smith
William O'Connor (challenger) v Michael van Gerwen
Gerwyn Price v Peter Wright