Ronnie O'Sullivan is in danger of falling victim to one of the biggest shocks in Crucible history as he trails amateur James Cahill 5-4 in their World Championship first-round match.
Cahill, 23, settled immediately against the world number one to go 1-0 up.
He then trailed the five-time champion 2-1, 3-2 and 4-3, but came back on each occasion and pinched frame nine.
Cahill needs five more frames for victory when the match resumes at 10:00 BST on Tuesday.
Debutant qualifier Cahill, the first amateur to play at the Crucible, showed great resilience to stay in the match when many would have crumbled.
A confident start saw him win the opening frame with a brilliant pot on the black.