Manly has blown a 16-4 lead late in the first half to end up losing 30-24 to the Dolphins at Lang Park.
However, far more damaging could be an injury to fullback Tom Trbojevic, who limped from the field mid way through the second half with a hamstring injury.
Depending on the injury's severity, Trbojevic could be a doubt for the Blues' State of Origin campaign, with Manly confirming scans would take place on Friday.
"It's hamstring, not sure how bad it is," Manly head coach Anthony Seibold said after the match.
The Dolphins also saw winger Jason Saab leave the field with a suspected grade three AC joint injury late in the first half.
"We've lost both those guys for a period of time, obviously," Seibold added.
The Dolphins scored three tries in five minutes before half-time to take the lead, the second of which was a stunning solo effort from five-game fullback Trai Fuller, who chipped ahead and regathered under the posts in dastardly wet and slippery conditions.
The dramatic shift in the contest came just a week after the Sea Eagles coughed up a 20-0 lead early in the first half against Canberra.
The Dolphins a 20-16 lead at half time and, although Trbojevic scored for Manly soon after the break, the momentum swing back to Manly never came, as neither side was able to pull away throughout a tense second half.
Jack Bostock's score in the corner re-established the hosts the lead, while indirectly led to Trbojevic's injury, as the Manly fullback raced across to cut him off, missing and colliding with a camera man.
"The five minutes before half-time were way off," Seibold said.
"I thought we played decent footy for 35 minutes."
The victory sees the Dolphins win back-to-back games for just the second time this season, keeping them in fourth spot on the NRL ladder.
Look back on how all the action unfolded in our live blog.
Thanks for being with us tonight.
We will be back tomorrow for more NRL action, and make sure you check back to this page for the results of Tom Trbojevic's scans.
Manly assure us we will be hold as soon as they know in the morning - and as soon as we know, we'll let you know.
Here's Wayne Bennett.
"We didn't play well ... [but] we got the two points and that's what we came for," he says.
"Putting two wins together is important."
Bennett pays credit to Trai Fuller, describing him as a "special player" and saying that he's not sure how he will fit him into the team when Hamiso Tabuai-Fidow returns.
"That's a good question, I don't have an answer."
He adds that Herbie Farnworth was "good" on his return.
"Herbie was good. I didn't think he was outstanding but he was good."
"We are a good footy side," Seibold says.
"We've just got to play our best footy for longer periods.
"Every game apart from the Dragons game we've put ourselves in a position to win the game."
Seibold says he's not sure how bad Tom Trbojevic's injury is, but he will likely be without both him and Jason Saab for a while.
"It's hamstring, not sure how bad it is," Seibold says of Trbojevic.
"We've lost both those guys for a period of time, obviously.
"We had a few guys out already tonight. With Saab and Turbo going down tonight it puts a pretty big hit in our squad.
"There is a group there that really cares about the football team."
Here's Anthony Seibold.
"It was really disappointing, that five minutes before half time cost us the game," he says.
"The five minutes before half time were way off.
"I thought we played decent footy for 35 minutes."
Daly Cherry Evans admits it is "frustrating talking about the same thing" as last week.
"It's something we need to fix. We've got to change a few things. We can fix it, we've just got to work harder at it."
Thanks Simon, a great game to kick-off the weekend.
- Mike
Considering the conditions, I did not expect such an intense game with such genuine quality in it.
I should have, given these two teams were fourth and fifth of the ladder coming in, but it was still impressive.
Especially given the conditions - it was sopping wet out there.
Credit to both sets of players.
Dolphins come away with the competition points, but the big news is the injury to Tom Trbojevic, and its possible severity with Origin just around the corner.
The fullback left the field in the second half after attempting to stop the Dolphins score their match-winning try late in the second half.
What that means, only scans will tell, but the Manly star will be praying he is not set for a fifth stint on the sidelines with a hamstring injury.
That should not take away from a tremendous performance from the Dolphins though, who win back-to-back games to solidify their spot in the top four.
Their three-try burst in the space of five minutes before the break was fantastic - part of an incredible turnaround from 16-4 down to being 20-16 up.
It's the second week in a row that Manly have had a sizable lead in the first half hour, only to end up losing.
Ethan Bullemor
has been placed on report for working the neck of Herbie Farnworth in the tackle as the Dolphins challenged the line.
Isaako has a chance to make it a six-point game, and does so.
Dolphins lead 30-24.
Just over 14,000 in the house tonight, we've just been told.
Tommy Talau
has come so close to scoring in the corner!
It was a brilliant pass out to him but he has stumbled as he's taken it - falling forward, he loses the ball as it hits the ground.
The Bunker is checking - and he does in face regather it - but was bundled into touch.
Huge defensive effort from the Dolphins, who lead 28-24.
Manly gets a penalty after Luke Brooks runs straight into Kurt Donoghoe after kicking through - I'm not sure where Donoghue was meant to go to be honest - but that's how Ashley Klein has seen it.
Tom Trbojevic has had to go from the field.
He came across to try and tackle Jack Bostock, and then hit the camera man on the sideline.
He stayed down and then walked away with a limp, seeming to favour his left side.
Fox Sports are reporting that it's a hamstring injury from the sideline.
A brilliant finish by Jack Bostock in the corner! One handed and diving as the Dolphins attack down the right.
A huge kick from the sideline from Isaako - and he nails it!
His kicking has not been great this year, or tonight, but he's great there.
Josh Aloiai has hit Max Plath as the Dolphins lock was falling forward.
It was a solid hit and it will result in Plath leaving the field for an HIA but I don't really see what Aloiai could have done about it - Plath was falling forward.
It will be a penalty and that's it.
Felise Kaufusi is pinged for a late tackle on Tom Trbojevic now and Daly Cherry-Evans opts to kick the points.
Reuben Garrick 30 metres out, kicks the points to make it 24-22.
About 12 metres out from his own line after fielding a kick forward.
Manly has challenged, but this looks like a clear knock on...
Oh, hang on, it's been overturned!
There is a slight piece of contact to Trbojevic's head as he was tackled initially and it is that the Bunker has decided is illegal.
That looks very, very soft.
He will be OK to continue but is limping around in backplay, the key Blues star.
We'll keep our eyes on his involvement over the next few minutes.
It's getting a bit dry - turn the sprinklers on.
- Flipper
The Dolphins level things up off the kicking tee after Ben Trbojevic was caught inside 10 metres.
We're locked at 22-22.
Reuben Garrick knocks on after the Dolphins work another two-kick fifth-tackle option - Jamayne Isaako kicking the ball the second time.
There may have been some suggestion that Herbie Farnworth was pulled back as he attempted to score - but I think he just slipped.
It's Turbo Tom Trbojevic!
Manly work the left side, the Dolphins right edge defence has been a bit shaky all night and it was exposed again.
This time, the key to unlock the defence was a brilliant offload from Jake Trbojevic to his brother who dived over to score.
That's the two teams all square, and now the Sea Eagles edge ahead as Reuben Garrick scores the extras.
It's 22-20.
Sports content to make you think... or allow you not to. A newsletter delivered each Saturday.
Add Category