Having missed with two earlier attempts at the match-winner both in regulation and golden point, Sandow piloted over the shot from 30 metres with 34 seconds remaining to finally separate the two sides at the bottom of the ladder.
Seemingly gone, trailing 18-6 with just 12 minutes remaining, veteran Nathan Hindmarsh inspired a stunning Eels revival as he wound back the clock with a bust down the short side to send fellow impending retiree Luke Burt over under the posts.
Hindmarsh then layed on the crucial ball for Fuifui Moimoi charging downfield, the big prop eventually finding Jarryd Hayne to lock it up with six minutes to go.
Sandow and Harry Siejka both pushed field goal attempts wide before extra time, Lachlan Coote's blushes saved in the extra period when Ken Sio was millimetres too late to grounding a ball the Panthers fullback desperately wanted to roll dead.
Penrith dominated the opening period but a try to Eels centre Ryan Morgan just before the break meant they had nothing to show for it as they went to the sheds locked at 6-6.
Having had few cracks at the Panthers line, the Eels went from deep in their own territory as Joseph Paulo put Morgan away - three defenders left in his wake in a 55 metre run top the line.
The Panthers signalled their intentions to attack Parramatta's right edge early in the contest, and it paid dividends with Luke Lewis scything over ten minutes in.
But despite numerous half breaks and a 6-1 penalty count in their favour they were unable to add to their tally, Coote kicking the ball out of Ken Sio's hands as he attempted to score in the corner.
The momentum of Morgan's try carried over into the second half as the Eels pushed for a lead, and it got worse for the Panthers as Luke Walsh left the field with a subluxed shoulder on 50 minutes.
Then Etu Uaisele turned the game when Jarryd Hayne fumbled after having a look at Penrith defence, Uaisele picking up the scraps and racing 85 metres to score.
It was a play which changed the game as David Simmons crossed three minutes later - the 18-6 scoreline more indicative of the home side's domination before Parramatta's late comeback.
Cowboys coach Neil Henry believes fullback Matt Bowen will let no-one down if State of Origin selectors choose him to replace the injured Billy Slater, after a stunning playmaking display against Canberra in Townsville.
With Queensland selector Des Morris in the stands, Bowen took on much of his team's playmaking responsibility, playing the last pass in four of the Cowboys' seven tries as they rolled on to a 40-18 NRL win on Saturday.
After a slow start when the Raiders got on the scoreboard in the fourth minute through Jarrod Croker, Bowen set up tries to Ashley Graham, Glenn Hall and Antonio Winterstein within the following 15 minutes to give the Cowboys a commanding 30-6 halftime lead.
And it was that first-half performance that Henry believes could turn the selectors' eyes towards the 30-year-old Cowboys fullback.
"He wouldn't let anyone down, he's in good form and that's obviously for Mal and the selectors to decide so they'll make their decision there," Henry said.
"But GI (Greg Inglis) was good at fullback (for Souths against the Broncos) as well so it's whether or not Dane Nielsen comes in but I know Mango (Bowen) is playing good football and he's got a good combination with JT (Thurston) so they wouldn't be out of place."
Henry praised his players for overcoming the sadness surrounding the death of the mother of co-captain Matt Scott and a slow start to put themselves back into the game.
"It got a bit scrappy in the second half and we conceded a few tries which we're not real happy about but it was a good win in the end," Henry said.
The Cowboys punished an error-riddled Raiders in the first half to put on five tries - Canberra completing just six of their 13 sets and making seven errors - and looked set to continue the rout in the second half after a 49th minute try to Kane Linnett.
But Canberra side responded with two tries in 10 minutes to Josh Dugan and Blake Ferguson.
The Cowboys then started to win back possession and second rower Scott Bolton extended the lead to 22-points after taking an Aaron Payne short ball and crossing underneath the posts in the final minute.
Coach David Furner said he was encouraged by the second half fightback but conceded by then the match was already lost.
"I think the frustrating thing is those errors," he said.
"That puts a lot of pressure on us and I think in the first half we could have defended those errors as well, it's going to happen in a game and we didn't.
"We did a better job of it in the second half."
Furner said Dugan would get scans on his injured right ankle when he returned to Canberra, after the five-eighth was stretchered from the field with in the 76th minute, but was hoping for the best.
"We're not too sure at the moment but he'll have a scan but they're talking about a syndesmosis or a sprained ankle, hopefully it's just that," he said.
The Canberra five-eighth was not the Raiders only injury concern, with second rower Joel Thompson coming off in the first half with a suspected broken arm.