Michael Smith held off a concerted fightback to beat reigning Unibet Premier League champion Michael Van Gerwen 7-4 in Exeter.
Smith, who hit a nine-darter in Dublin last week, raced into a 6-1 lead, landing a 134 check-out on the way, but saw the five-times winner take the next three legs before he eventually eased his way over the line.
Luke Humphries had earlier became the first challenger to win a Premier League match as he defeated former world champion Gary Anderson in a tense conclusion.
The 25-year-old secured a 7-5 victory over the Scot, whose finishing deserted him, claiming a landmark win by hitting double one having earlier completed a 100 check-out which included two double tops to tie the match a 5-5.
Humphries told Sky Sports: "I've never been so nervous in my life. I really wanted to be the first challenger to win - I think I let it get to me a little bit too much in the end there. I was trying well too hard throughout the whole game.
"I know I didn't play my best game there - Gary definitely didn't - but to be the first winner just proves that we can do it."
Glen Durrant turned in an impressive display to dispense with the previously unbeaten Gerwyn Price in 10 legs.
Durrant raced into a 4-0 lead and had darts to take the fifth, and although Price scraped his way back into it, the man from Middlesbrough clinched a convincing 7-3 win with a 129 check-out.
World champion Peter Wright was similarly dominant as bounced back from last week's 7-1 defeat by Price to beat Nathan Aspinall 7-3.
Despite losing the opening leg after missing the bull as he attempted a 170 finish, Wright took the next three and never looked back, averaging 110 on his way to victory.
Daryl Gurney had to fight all the way to secure just his second point of the tournament from a 6-6 draw with Rob Cross.
The Northern Irishman led 3-0 after taking the first and third legs against the darts, but after losing the next four on the trot, had to repeat the feat in the 12th to secure a share of the spoils.