The 18-year-old Trueman, who played in the academy Grand Final at the DW Stadium a fortnight earlier, was drafted in for his full Super League debut on the same ground following the loss of Gale with an appendectomy and he seized his chance in remarkable fashion with an 18-minute hat-trick.
Winger Greg Eden gave the Tigers an early lead with his 38th try of the season, putting him in sight of Denny Solomona’s Super League record of 40, before it became the Trueman show as the Tigers romped to a third win of the season over the reigning champions.
Wigan, who were without hugely-influential skipper Sean O’Loughlin, produced a spirited fightback after trailing 26-0 but it was in vain and they now need other results in the final round of Super 8s matches to go their way before they take on Wakefield in their last game on Saturday to keep their title defence alive.
It took Trueman just four minutes to make his mark, which was about as much time as he spent on the field on his debut against St Helens in June.
The youngster showed great vision by kicking ahead on a free play following the first of a series of handling errors by Wigan to enable Eden to open the scoring.
With passions running high, referee Ben Thaler twice lectured the captains in an attempt to calm tempers and placed Wigan prop Tony Clubb on report for a tackle that forced loose forward Nathan Massey off with concussion.
The Warriors could hardly get out of their own half in the first half and Trueman soon made the pressure count.
He raced onto hooker Adam Milner’s grubber kick to score his first Super League try on 15 minutes and swooped on a loose ball eight minutes later to double his tally.
Milner then lost the ball going for the line before Trueman completed his hat-trick and McShane kicked his second conversion to make it 20-0 after 32 minutes.
There seemed no way back for the home side when centre Jake Webster squeezed a pass out of the tackle for right winger Greg Minikin to score Castleford’s fifth try five minutes into the second half, with McShane taking the score out to 26-0 with his third goal.
But Wigan’s right winger Tom Davies gave them hope on 52 minutes when he produced an exceptional finish to claim his 13th try of the season and Sam Tomkins quickly added another after winning the race to George Williams’ kick.
Wigan lost a limping Joe Burgess but cut the deficit further when scrum-half Thomas Leuluai jinked his way through for a solo try on 61 minutes and Williams kicked his second conversion.
Both Joel Tomkins and Clubb were held up over the line as the Warriors maintained the pressure but Castleford captain Michael Shenton made sure of the win when he glided through the home defence on 69 minutes.
Second rower Willie Isa pulled another try back for Wigan but the Yorkshiremen had the final say when Minikin scored in the last minute and McShane took his goal tally to five from seven attempts.