In-form Michael van Gerwen and two-time UK Open champion James Wade stormed into the last 16 with comfortable wins on Saturday afternoon, while Scottish pair Robert Thornton and John Henderson also reached the fifth round in Bolton.
Wade swept past Dave Chisnall, winning 9-2 to keep alive his hopes of winning a third UK Open title.
But the 2008 and 2011 winner, who has won five games to reach the last 16, insisted he is not thinking that far ahead.
He said: “I’m looking forward to my next game, whoever it is against, and that is all I’m going to concentrate on at the moment.
“It’s not about this tournament or any individual tournament for me. It is all about getting things right for a good future in the modern era of darts.
“I’m happy with my results so far and if I step my performance levels up a little bit I can beat anyone.”
Wade will take on Henderson in the evening session for a place in Sunday’s quarter-finals after the Scotsman fought back from 8-6 down to defeat Kevin McDine in a deciding leg.
“It’s a massive win for me,” said Henderson.
“It was very tense at the end and we both missed darts for the match but I was over moon when the last one went in.
“I’m really enjoying this tournament and it is onwards an upwards for me now.”
van Gerwen will face Terry Jenkins in round five after the Dutchman saw off Northern Ireland’s Michael Mansell 9-3.
And the world number two is targeting an improved performance.
“I’m not too happy with how I played in the first two games,” said van Gerwen, who had beaten Mervyn King on Friday.
“I have to concentrate better tonight. Terry is a great player and hopefully that will bring out the best in me.”
Defending champion Robert Thornton won the last four legs to claim a 9-5 win over Kirk Shepherd.
The Premier League star, who will face Raymond van Barneveld on Saturday night admitted he had to work hard for the win.
Thornton said: “Kirk is one of those players who will throw a brilliant leg and then a bad leg so when he puts a run together you can be in trouble.
“I dug in and got the job done though. I played fairly well and I’m happy to be through.
“My game is there and so is my confidence and I’m actually playing better than I did when I won it last year.”
van Barneveld won his fourth round match comfortably, defeating Joey Palfreyman 9-3.
By Chris Murphy
SEE JAMES WADE, RAYMOND VAN BARNEVELD, SIMON WHITLOCK AND TED HANKEY LIVE IN SUNDERLAND ON JUNE 15 – TICKETS AVAILABLE HERE