A subdued Selby – seemingly jaded after a gruelling semi-final win over Ding Junhui on Saturday – trailed 10-4 to John Higgins in their best-of-35-frame final.
But, the world No 1 refused to wilt, scrambling in breaks of 81 and 121 to cut the deficit to 10-7 heading into today’s final two sessions.
Higgins had enjoyed a comfortable semi-final route against Barry Hawkins, and started the better as he chased a fifth Crucible crown.
Heading into the two-day match, Higgins had predicted Selby might one day match Stephen Hendry’s record of seven Crucible titles.
But Higgins, who at 41 is the oldest finalist since 49-year-old Ray Reardon lost to Alex Higgins in 1982, is determined to prevent the Leicester cueman landing title number three this year.
And he ruthlessly capitalised on an unusually poor start from Selby to snatch a 6-2 lead after the first session in Sheffield.
The best-of-35-frame match in theory allows a player to recover from such deficits, as Dennis Taylor proved when coming back from 8-0 adrift of Steve Davis in their 1985 final.
But records show that no player has come back to win from a first-session deficit as wide as 6-2 to take the title since that famous Taylor fightback.
In his first world final since 2011, when he beat Judd Trump, Higgins showed vintage class with a total clearance of 141 in frame four, just two points shy of his highest ever Crucible break.
Runs of 63 and 95 saw him pull 4-2 ahead of Selby, who should have cut the gap but missed a red when 54-1 ahead in the next frame and a clearance of 58 from his opponent was immaculate.
Such sessions from Selby are rare, and for Higgins it was important he took full advantage, so by edging frame eight it struck a major blow.
Higgins and Selby remained four frames apart at the mid-session interval in the evening. Selby remained erratic and lacking in spark, but he made his highest break of the match so far, an 86, and scrapped through frame 12 to trail 8-4 as they headed to the dressing rooms.
At 10-4, the history books were being reached for, before Selby took the final three frames of the evening to keep his title hopes alive.
Higgins knows all about Selby’s battling qualities, and came into the match singing his praises.
“He could be the one right now who could challenge Hendry’s seven titles,” said Higgins. “If he goes ahead and beats me, it’d be his third and he’s still a young man. But he’s not like Hendry as a player – Hendry couldn’t win the tough frames, he’d blow you away. Mark’s more like Steve Davis.”
Higgins called Selby “a big favourite” for the title. Such remarks were probably designed to lift pressure from his own shoulders, with Higgins quietly confident he stood an outstanding chance of lifting the trophy tonight.
“I’m very proud to be in my sixth world final, and it’s a great feeling to be going for my fifth world title,” said the 41-year-old Scot.
In his third final, back in 2007, Higgins beat a 23-year-old Selby who had come through qualifying before making a surprise run through the draw.
“After that tournament I told him, ‘I know you’re disappointed but don’t be because you’re definitely going to come back and win this thing’,” recalled Higgins.
“He’s proven that, and now he’s going for his third one and he’s going to maybe be emulating Steve Davis and Stephen Hendry by retaining it. He’s a special player.”
Selby’s memory of that match are foggy, but he remembers well that the third session of the match had to be clipped two frames short because of the pedestrian pace. The match finished at almost 1am on the Tuesday morning.
“I remember I got back from 12-4 to 12-10 and we were pulled off, which doesn’t surprise me, the way I play,” said Selby.
“John seemed to be mentally not with it, missing a lot of easy balls and giving me chance after chance. I’d have probably come out 12-12 from that session and who knows, it might have been my year then. To get to that final so young I think stood me in good stead for the future.”
In recent years Selby has become the dominant player in the sport, and landing world titles in 2014 and 2016 have established him ahead of the likes of Higgins and Ronnie O’Sullivan as the man to beat.
He is enjoying an unbroken two-year spell as world No 1, but it will be tough to sustain the level of success, just as Higgins has found.
“Everyone has blips in their career where they go through bad patches and John’s been no different,” said Selby.
“But when he’s at his peak he’s one of the greatest of all time.”