Wishaw's John Higgins is trailing world number one Ronnie O'Sullivan 10-6 at the World Snooker Championship.
The Lanarkshire potter had the game at 4-4 but his opponent - who is a six-time champion - made five half centuries to gain a 9-6 advantage.
Higgins made a few loose shots and it proved costly as his foe managed to make it a four frame advantage at the end of Friday's session.
