Gary Anderson defeated Terry Jenkins in the all-Unicorn quarter final clash to go through to the semi-finals.
However, Anderson was made to sweat before sealing his 16-12 win.
The Scot hit ten 180s and finished the game with an average of 99.97, with a mid-game burst which saw him win seven out of eight legs proving crucial before Jenkins hit back from 13-7 down to cause him some anxious moments.
"I'm relieved to have got through that," said Anderson. "Terry's best form is returning and he kept coming back at me.
"I knew there were a lot of 140s and 180s from me but the doubles are the main thing and I missed too many. I thought I was going to blow it at the end and started panicking, but I had a good winning leg."
In the afternoon’s other quarter final Mark Walsh enjoyed a fine 16-14 victory over Ted Hankey.
Saturday's evening session sees the remaining two quarter-finals, as PDC World Champion Adrian Lewis plays former Lakeside Champion Mark Webster before three-time Grand Slam winner Phil Taylor meets Paul Nicholson in the second all-Unicorn clash of the day.
William Hill Grand Slam of Darts
Quarter-Finals
Saturday November 19
Afternoon Session
Ted Hankey 14-16 Mark Walsh
Gary Anderson 16-12 Terry Jenkins
Evening Session (7pm)
Mark Webster v Adrian Lewis
Phil Taylor v Paul Nicholson
Best of 31 legs
Photos courtesy Lawrence Lustig / PDC