Simon Whitlock thrashed Rob Cross 7-1 in Cardiff, leaving the PDC world champion still without a Premier League point after two matches.
Defending champion Michael van Gerwen was also beaten, losing 7-5 to Peter Wright in a repeat of the 2017 final.
Australia's Whitlock and England's Michael Smith, who beat Daryl Gurney 7-4, are the only two players to have won their first two group fixtures.
Gary Anderson and Raymond van Barneveld were Thursday's other victors.
Anderson overcame Welshman Gerwyn Price 7-3 for his first win of this season's competition, while Van Barneveld defeated Mensur Suljovic 7-5.
Sussex thrower Cross, 27, lost to world number one Van Gerwen in his opening match and will aim to earn his first point of the tournament when he faces Wright in Newcastle on 15 February.
Round two results
Michael Smith 7-4 Daryl Gurney
Rob Cross 1-7 Simon Whitlock
Michael van Gerwen 5-7 Peter Wright
Gerwyn Price 3-7 Gary Anderson
Raymond van Barneveld 7-5 Mensur Suljovic