Melbourne centre Will Chambers scored in the final minute to snatch a 20-18 win from the jaws of the Sharks in their NRL clash at AAMI Park.
Melbourne fought back from 18-10 with two minutes remaining, with second rower Ryan Hoffman scoring and then Chambers for the heart-stopping win.
It was heart-break for the Sharks, who deserved the victory.
Instead of the visitors locking down sixth position, the Storm were celebrating securing a top two position ahead of the looming NRL finals.
Melbourne trailed 6-4 at halftime and the margin should have been greater with the home side only managing to complete 55 per cent of their sets in a scrappy, uncharacteristic performance.
The Sharks looked like they had snuffed the Storm's fightback in the space of two minutes midway through the second half.
Five-eighth Gareth Widdop was denied a try in the 62nd minute when video referee Chris Ward ruled that Hoffman had obstructed would-be tackler Bryce Gibbs.
The Sharks then took advantage of the penalty and in the ensuing set Ward gave the green light to a try by fullback Isaac Gordon, who managed to get the ball across the line for an eight-point turnaround.
That gave the visitors an 18-10 lead and through stiff, gutsy defence they were able to repel the Storm's try-scoring efforts until the 78th minute.
Hoffman got the ball down to give his side the whiff of victory but it still looked like it would be too little too late.
Billy Slater, who set up the first try of the match, showed his champion qualities as he made a break and the ball made it way out to Sisa Waqa, who found Chambers outside for the match-winner.
It was a big match for Fijian winger Waqa, who also scored the opening try.
Cronulla coach Shane Flanagan said he had mixed emotions as he was happy with his side's effort for all but the final five minutes of the game.
"The boys tried their backsides off for 75 minutes ... that last five is something I'd like to forget," he said post-match.
He said while the loss wouldn't cost them a place in the finals, it could cost them a home final if they don't manage to win and finish sixth in their last round match against the Cowboys.
Skipper Paul Gallen said the performance showed his team could compete with the top teams in the competition.
"The biggest thing for us is that we learn from that," Gallen said.
"The game goes for 80 minutes not 75, that's what we need to learn."
Melbourne coach Craig Bellamy admitted he'd given up hope his team would get up for a win.
"With five (minutes) to go I basically put my hands up when Sika (Manu) dropped the ball on the tryline, I thought that was it but the players didn't so that's a good sign," Bellamy said.
"We were really lucky.
"We need to fix up our attack, we couldn't hang on to the ball in the first half; just really simple errors from individuals."
Skipper Cameron Smith addressed his troops on the field following the win and told them it was a great effort.
"It take a special effort from a special team to get that result from the way we played and where we were with five minutes to go," Smith said.
The Storm finish the regular season with a match against Wests Tigers next Saturday night in Sydney.
