Kent qualifier Kirk Shepherd caused the biggest upset of the PDC World Championships so far after knocking out number four seed Terry Jenkins.
Fourth seed Jenkins faltered at 2-1 up and allowed Shepherd in to level
Jenkins failed to find victory even though he had seven darts at doubles to clinch the match in the fourth.
Shepherd, 21, duly recovered from 2-1 down at Alexandra Palace to reach the second round in a five-set thriller.
Another qualifier, Jamie Caven, also registered a shock with straight-sets win over Wes Newton on day three.
The 31-year-old dropped just four legs on his way into round two, where he will meet Wayne Mardle on Saturday.
"I'm thrilled to bits," he said. "I came here to enjoy myself but I think I justified being up there."
Jenkins is the second big-name casualty in the tournament following Monday's elimination of Colin Lloyd.
The much anticipated all-Irish battle saw Mick McGowan triumph 3-0 over Jason Barry, who missed a series of doubles.
In other matches, Barbados' Anthony Forde set up a clash with world champion Raymond van Barneveld with a 5-2 win over Japan's Akihiro Nagakawa in his preliminary-round game.
Denis Ovens' challenge began well as he took nine successive legs to whitewash Colin Monk.
Meanwhile Barrie Bates dropped just one leg against Canada's Gerry Convery and Czech champion Miloslav Navratil also whitewashed Philippines qualifier Rizal Barellano.
The day's final two games saw 18th seed Chris Mason beat Steve Brown 3-1 and 2004 finalist Kevin Painter, the 15th seed, overcome Gary Mawson 3-0, dropping just two legs in the process.