A sideline penalty-goal attempt from stand-in goalkicker, halfback and captain Apisai Koroisau from 30 metres out ricocheted off the crossbar and scraped over to break the deadlock with three minutes left on the clock on Saturday.
The Tigers then held on in the desperate closing stages to snap a depressing 10-match losing streak stretching back to mid-May and end a week of upheaval and turmoil with renewed hope.
With the departing Tim Sheens officially still head coach until season's end, Marshall won't be credited with his maiden win as an NRL head coach - but diehard fans will certainly take it.
"It's not about me, to be honest," Marshall said after only being thrust into the hot seat for the final three rounds on Thursday.
"I'm still the assistant coach. The bosses sent me to get practice for next year, to see what it's like and owning these duties.
"This three weeks is about us finishing off as a club how we want to finish and today we just needed a result.
"We've been there or thereabouts for a few weeks now but we just couldn't get over the line.
"So to have the skipper step up from the sideline, 30 out and knock it over with a bit of drama and get the end result, we needed it.
"It was a crazy finish."
Koroisau revealed he'd had a bet with teammate Brandon Wakeham only two days ago that he'd kick a goal from the "exact spot".
"So, yeah, I knew when the call came down to back myself so I thought I'd take the kick," he said.
"As soon as it came off the boot, my head was down straight away because I was praying. I knew it wasn't the best strike so thankfully it went over."
Incredibly, the hapless joint venture side hadn't tasted success since romping to a record 66-18 win over North Queensland in round 12.
The victory, which sent the near-10,000 home fans at CommBank Stadium into raptures, also offers the Tigers the chance to avoid a second straight wooden spoon after St George Illawarra lost 36-28 to Melbourne on Saturday night
Sitting two competition points behind St George Illawarra, the Tigers still must beat the Sydney Roosters and Manly in their remaining two games and sweat on the Dragons falling to the Warriors and Newcastle to avert another last-place finish.
But with premiership-winning club legend Marshall taking full control a year earlier than had been planned, suddenly the Tigers faithful have reason to believe.
For the injury-hit Dolphins, it was a bitterly disappointing defeat.
A field goal from winger Jamayne Isaako with five minutes remaining had earned the Dolphins a 23-22 lead, which looked like consigning the Tigers to an 11th consecutive loss.
Instead Koroisau stepped up to become the hero.
He was only kicking - and playing halfback - after regular No.7 and Manly-bound star Luke Brooks was ruled out with a calf injury.
The Tigers looked like doing it easily when stand-in hooker Jake Simpkin dived over from dummy half in the 56th minute to extend the home side's lead to eight points.
But they invited the Dolphins back in with a soft try to interchange sub Trai Fuller on debut and a sloppy penalty for an obstruction while in possession in front of their own posts.
Then the drama and excitement really unfolded in a showdown otherwise featuring two sides long out of the finals race.
10°C