Michael van Gerwen and Peter Wright became the first two players to secure Premier League play-off spots with wins in Birmingham.
League leader Van Gerwen took three points from his two games, drawing with Dave Chisnall before whitewashing Adrian Lewis 7-0.
Wright beat Phil Taylor 7-3 to stay second in the table.
Gary Anderson and Taylor are third and fourth, but Lewis' qualification chances were damaged by two defeats.
Having lost 7-4 to James Wade in Thursday's opening match, Stoke-on-Trent thrower Lewis had no answer to an imperious performance by defending Premier League champion Van Gerwen.
Anderson's 7-4 victory over Raymond van Barneveld left the veteran Dutchman one point outside the top four.
However, with each player having only two matches left in the group stage, only four points separate third-placed Anderson and Wade, who stayed bottom of the table despite his victory.
Premier League - round 13 results
James Wade (Eng) 7-4 Adrian Lewis (Eng)
Dave Chisnall (Eng) 6-6 Michael van Gerwen (Ned)
Phil Taylor (Eng) 3-7 Peter Wright (Sco)
Gary Anderson (Sco) 7-4 Raymond van Barneveld (Ned)
Adrian Lewis (Eng) 0-7 Michael van Gerwen (Ned)