Four-time champion Mark Selby has some work to do in his bid to make another Crucible final after he lost the opening session of a gripping semi-final against Mark Allen.
Selby, who outclassed legendary Scot John Higgins 13-7 in his quarter-final clash, continued where he left off and took the opening frame with a superb break of 123.
However, Allen hit back with two half-centuries and finished the session strongly, reeling off three consecutive frames to establish a crucial 5-3 advantage.
It is still relatively early days in this best-of-33 showdown, but the signs are good for Allen on his return to the one-table situation at the Crucible for the first time since 2009.
The Northern Irishman is 4/5 to convert his first-session lead and go on and make the final with Selby, who is competing in his eighth semi-final in snooker's blue-riband event, an 1/1 chance to overcome the deficit.
The winner will face either Ronnie O'Sullivan's conqueror Luca Brecel or Si Jiahui, who is the first debutant to reach the semi-final stage for 28 years, in the title decider.
|Mark Allen v Mark Selby
|Crucible Theatre, Sheffield
|14:30 Friday, 10:00 & 19:00 Saturday
|How to watch
|bet365 Live Streaming, BBC and Eurosport
|Mark Allen 4/5, Mark Selby 1/1
Despite not being at his best so far in the 2023 World Snooker Championships, Allen has found a way to win and the season's form man did a job on Selby in the opening session.
It has been a remarkable season for Allen, who is chasing a fourth title having already lifted the Northern Ireland Open, UK Championship and World Grand Prix.
But the Pistol's last title triumph came back in January and it was evident that his levels had dropped in recent tournaments.
Throw in an horrendous Crucible record, which has seen him make the semi-final only once and way back in 2009, and it was difficult to have maximum faith in the fourth seed.
Allen benefitted from poor performances from Fan Zhengyi and Stuart Bingham in the opening two rounds and then was being severely tested by Crucible debutant Jak Jones in the quarter-final until the Welshman blinked in the final session, leaving the Northern Irishman the chance to prevail 13-10.
That is part of the reason why Selby came into this semi-final contest as a strong favourite, but Allen has again shown write him off at your peril.
The Pistol matched Selby in the tactical department, an area where the 22-time ranking-title winner is usually so dominant and punished his mistakes with some composed clearances.
The 37-year-old played solid snooker throughout and, on the whole, was fully deserving of his 5-3 lead after making breaks of 63, 66, 64, 60 and 78.
However, Selby came from 4-1 down against Higgins in his quarter-final to win 13-7 and also found himself locked level at 6-6 with Gary Wilson in round two, before stamping his authority to triumph by six frames.
So Selby followers shouldn't be too concerned just yet, especially given this semi-final is first to 17 and the Jester from Leicester is considered a Crucible specialist.
Selby is a four-time world champion, featuring in his eighth semi-final, and those past Sheffield experiences could be invaluable.
The world number two arrived at the Crucible operating at the top of his game, having won the WST Classic in his home city of Leicester before finishing runner-up to Shaun Murphy at the Tour Championship in Hull.
And wins over Matt Selt, Wilson and Higgins in Sheffield have done little to suggest his levels have dropped, so he will be confident he can overcome the early deficit.
There is still plenty of snooker to be played - Allen has to win 12 more frames to get over the line - so those looking to get involved should still have faith in Selby turning things around at 1/1.
One thing that does look certain is for this titanic tussle going long and it is 1/1 for the contest to feature at least 31 frames, which would mean a 17-14 win or better either way would reward punters.
There has also been only one century so far, but expect the scoring to improve as the tension goes away.
That said, the century line is 4.5 which looks a tad too high given these two will attempt to cancel one another out, making unders the potential play at 10/11.