Without a win since round 18 last year, it looked like being another frustrating night for the 8652 fans who braved the Toyota Stadium wet when Nathan Gardner spilled the ball as he dived for the tryline after just six minutes.
Cronulla went on the attack again when Williams was put on report, and Jayson Bukuya got the home side on the board when he carried five defenders over the line.
Gardner made amends for his earlier miss when he capitalised on a clever Gallen offload, and when Ben Pomeroy crossed just after the half hour, the Sharks were up 16-0 and the Sea Eagles had completed just five sets.
Todd Carney nailed a field goal on the halftime siren which proved crucial later on, but there was little indication of the frantic finish that was to ensue as the Sharks retained control of proceedings.
Even when Michael Oldfield crossed for his first try on 63 minutes, it appeared a mountain too high - especially when Jamie Lyon missed the tough conversion - but when Brett Stewart somehow touched down on a Kieran Foran grubber five minutes from time, the impossible seemed possible.
Oldfield grabbed his second two minutes later as the Sea Eagles chanced their arm, but two late opportunities ended with fumbles as Manly fell short in the comeback bid.
Sharks coach Shane Flanagan admitted to some nervous moments late in the game.
"I was about to jump off the back of the grandstand,'' he said.
"Seriously, I had nightmares of last year - we led 13-0 with about ten minutes to go and they got us after the bell.
"I was just hoping the football gods weren't that cruel tonight.''
Of his skipper's performance, Flanagan said:
"Is anyone surprised? I'm not surprised, I know he's got a huge motor.
"He was back to his best tonight ... we're lucky to have him.''
Manly coach Geoff Toovey said his team failed to match Cronulla's enthusiasm early, but he didn't think there would be too many issues with Williams' dangerous throw.
"It's just one of those ones that went wrong, he put him in a dangerous position but he landed safely,'' Toovey said.
In an onfield interview with Triple M after the game, Williams too attempted to downplay the tackle.
"I just tried to get him down, it's just part of footy,'' Williams said.
"I just tried to make the tackle.''
- AAP