Centre Adam Doueihi ensured the Tigers brought down the curtain on one of most tumultuous periods in their recent history, kicking an 88th-minute penalty to send the Leichhardt Oval crowd of 14,182 into a frenzy.
But Sunday's game was all about Galvin.
Two weeks ago on Monday, Galvin set the NRL news cycle ablaze when the teenager informed his junior club he had no intention of renewing his contract beyond 2026.
The Tigers responded by dumping the prodigious 19-year-old to NSW Cup, with club chief executive Shane Richardson and coach Benji Marshall at loggerheads with Galvin's agent Isaac Moses.
Halfback Jarome Luai and fellow co-captain Api Koroisau were said to have welcomed Marshall's plans to demote Galvin to reserve grade.
But after the Tigers lost in an ill-disciplined defeat to Parramatta on Easter Monday, Marshall pulled rank and recalled Galvin to the NRL side after just a week-long exile.
Galvin set up the Tigers' opening try and rose to the occasion without Luai, who spent 15 second-half minutes undergoing a head injury assessment.
"That's the pressure reliever we needed," said Marshall, whose side moved to 4-4.
"I thought he (Galvin) was great, he just went out and played footy with that first try he set up that calmed the nerves.
"That's a season-defining win … we go to Magic Round (against St George Illawarra) and can catapult our season."
The Tigers' strong-arm stance and the reluctance of Galvin to extend his stay beyond November 1 appeared to have fanned the flames of discontent at the joint-venture club.
Veteran hooker Koroisau publicly clipped Galvin when he said: "When someone's heart is not in it, it's hard to take the field with them every week."
Luai and winger Sunia Turuva both took digs at the teenager on social media.
"(But) never once have I said I don't want to play with him," Luai said.
"I love playing with the kid and I love what he brings to this team. I'm proud of the boys.''
Galvin was greeted with light boos when the team list was read out to a packed Wayne Pearce Hill on Sunday, but that quickly died down when he set up Samuela Fainu for the opening try of the match.
There was extra scrutiny on Galvin's body language and interactions with his teammates upon his NRL recall.
But when winger Turuva jammed in off his wing to jolt the ball loose from Braydon Trindall, the five-eighth was first in to congratulate him.
Luai and Galvin then combined to set up Turuva for the Tigers' second, before Ronaldo Mulitalo jagged one back for the Sharks to cut the home side's lead to 10-6.
Douiehi booted a penalty after Luai was collared by Briton Nikora, who was sent to the sin bin in the 50th minute.
And while Galvin set up Tallyn Da Silva with a bomb, the Sharks rallied and hit back through Will Kennedy and Billy Burns.
Nicho Hynes converted both tries to lock the game up at 18-18 with 13 minutes left after Fonua Pole had been sin-binned for a high shot.
Hynes missed two regulation-time field-goal attempts, with one hitting the post and another charged down by Terrell May.
Jahream Bula blocked a third Hynes field-goal effort, before Doueihi shanked his attempt wide to see out the first half of golden point.
But Doueihi made amends when Tom Hazleton was penalised for having his hands in the ruck, and the Lebanese international sank the winner from right in front.
"The effort was there, and there was a lot to like about how we hung in there, but we needed to execute a bit better," said coach Craig Fitzgibbon, whose Sharks (4-4) side sit seventh.
