John Higgins maintained his two-frame World Championship semi-final advantage over Kyren Wilson after an intriguing evening session at the Crucible.
Higgins opened up a 12-9 lead, but Wilson responded with breaks of 106 and then 93 to get to within a frame of the Scot.
But Higgins rallied and a run of 91 saw him take a 13-11 lead into Saturday, where he needs only four frames to advance to the final.
Wilson trailed 9-7 going into the session and made an immediate statement with a break of 124 to halve the deficit.
Breaks of 56 and 75, though, saw Higgins give himself a three-frame cushion before Wilson again rallied with a run of 81 to take the fourth frame of the session.
Higgins responded to again stretch his lead, but Wilson's 50th century break of the season and then that 93 moved him within one again. Higgins kept his cool to win the final frame of the evening.
Two massive frames on the spin from @KyrenWilson!— World Snooker (@WorldSnooker1) May 4, 2018
📡 A superb 93 clearance puts him a frame behind Higgins, with one more frame left to play this session! [12-11]#ilovesnooker @Betfred pic.twitter.com/LKB56qJdHJ
Barry Hawkins showed the kind of defiance that could land him glory on Monday as he wrestled back control against Mark Williams in the other semi-final.
Two-time former winner Williams produced some sparkling snooker before the mid-session interval to reel in Hawkins from 5-3 and draw level at six frames each, and it seemed all the momentum was with the veteran Welshman.
But Hawkins returned from his dressing room rejuvenated and once more took a grip, moving 9-7 clear overnight in the best-of-33 clash of the two left-handers.
With Hawkins twitching and frowning from his seat, Williams scythed into his opponent's overnight lead.
A smooth opening 80 break set the early tone and, after they shared the next two frames, Williams struck again.
Both men were briefly distracted - Hawkins by an official's walkie-talkie blurting out a message as he played and missed a red, and Williams by untimely encouragement from a spectator before he failed to sink a brown.
After giving Hawkins a playful nudge when their paths crossed, seemingly in a nod to the barge controversy involving O'Sullivan and Carter last Saturday, Williams produced a stunning pot on a crucial red.
In trouble by the baulk cushion, Williams had to apply heavy swerve on the white to sink a ball 12 feet away, and it effectively won him the frame.
The interval was no help to the Welshman, though. The early fluency was gone and, when Hawkins doubled in the pink to make it three frames in a row it was a brutal blow.
Williams hit back with a precious 62 to ensure he would still be in the running on Saturday, when they play to a finish over morning and evening sessions.