World champion Mark Selby was stunned 6-3 by Ryan Day in the first round of the Players Championship.
Selby, 34, has been out of form since winning a third world title last year and he quickly found himself a frame down against Day, who opened the match with a century.
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Day, who has won the Gibraltar Open and Romanian Masters in the past few weeks, doubled his lead to put the pressure on his opponent.
Selby responded well with a break of 96 but Day took two more frames to open up a commanding 4-1 lead.
Back-to-back half-century breaks from Selby made things interesting before Day took the eighth frame.
The Welshman, who is on home soil, finished the match with a superb break of 133.
In the afternoon game Mark Williams produced three half-centuries including a high of 86 as he saw off Yan Bingtao 6-2.
The Northern Ireland Open winner won five of the opening six frames to maintain his good form and he quickly saw off his younger opponent.
The two Welshmen will now meet in the quarter-finals.
Earlier Shaun Murphy defeated Kyren Wilson 6-3 whilst Ding Junhui beat Masters champion Mark Allen 6-2.
In the late matches Luca Brecel faces off against Neil Robertson whilst the big draw will be Ronnie O’Sullivan’s first match of the tournament, as he plays Graeme Dott.
PLAYERS CHAMPIONSHIP FIRST ROUND RESULT
Shaun Murphy 6-3 Kyren Wilson
Ding Junhui 6-2 Mark Allen
Ryan Day 6-3 Mark Selby
Mark Williams 6-2 Yan Bingtao
Sparkling O'Sullivan sees off Murphy in Wales
O’Sullivan overcomes Trump, Murphy ousts McGill to reach last four