- Mark Selby bounces back against Ronnie O'Sullivan after second World Championship session
- Ronnie O’Sullivan in the running: How snooker 'morgue' has breathed life into world title bid
The duo had restarted their clash locked at 8-8 and the early exchanges of the evening's play followed that same pattern.
In the first frame of the session, a couple of superb reds set McGill up to move 9-8 ahead, only for Wilson to produce a break of 99 and level it up once more.
After McGill claimed a lengthy 19th frame to make it 10-9, Wilson came to life, claiming a tight 20th before a century put him ahead for the first time.
Kyren Wilson takes the 21th frame with a break of 116
He hammered home his advantage from there, skipping into a 13-10 lead thanks to his third and fourth straight frames.
McGill responded with a rapid-fire century of his own to cut the deficit to two ahead of the final session on Friday.
In the other semi-final, which has only seen two sessions of action, Mark Selby leads Ronnie O'Sullivan 9-7.